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RAM Memory Problems and Solutions: DDR/DDR2/DDR3 RAM - Windows XP, Vista, Windows 7


This section of this website provides the answers to questions about or solutions to computer problems caused by RAM memory, which always has to function 100% if the computer it is installed in is to function properly.

Click here! to skip the following informative preamble that provides useful diagnostic information and go directly to the list of solved RAM problems on this page.

If the memory is even slightly faulty, all kinds of software and hardware problems can result that can initially seem to have causes other than faulty memory. RAM memory that is not functioning properly is the most common cause of patternless system instability that can make it look as if there are all kinds of causes - overheating components, a faulty power supply, virus infection, software corruption, hardware problems that could be caused by any number of components or devices. Therefore, you should run the Windows Memory Diagnostic tool (links provided in the next item on this page) for a computer running Windows XP, Vista and Win 7 when it is experiencing erratic crashes, hangups or other abnormal behaviour that doesn't appear to have a diagnosable cause.

If you use the computer for work, it is advisable to run the Memory Diagnostic tool once or twice a year because it can discover that memory is going bad before it starts to affect the system noticeably. It can then be replaced before it screws things up in a big way. For example, backups or system images may not be restored properly or may be usable after they are restored if they were created on a system that has faulty memory. The effects of faulty memory could make you restore a faulty backup or system image (made that way by faulty memory) to fix the problem when the real problem was only faulty memory. If you don't have a good backup or system image or recovery disc, you will then have to reinstall everything - Windows and all of your software and data files from scratch - which could take days. That is why you should always also store your data files on a flash drive or on an online backup service, such as Microsoft's Skydrive that everyone with a hotmail account has access to, most of which are free up to a set storage limit.

Visit the Software: Backup Methods and Strategies: How to Make Restorable Backups, System Images page on this website for detailed information on those backup topics.

The range of questions and problems cover memory running slower than it should, overclocking memory, the full amount of memory isn't being reported, the computer reboots constantly due to faulty memory, motherboard-memory compatibility problems, how to identify the type and amount of memory being used by a computer, upgrading advice, etc. If you can't find the memory problem that brought you to this page, press the Ctrl + F keys to bring up the Find feature provided by your web browser and enter the search query that you used - or the most significant words in it.

The RAM memory questions and problems in the form of questions and answers (Q&As) are linked to below the initial useful information. Each descriptive link includes as much information as possible to make finding what you are looking for as simple and easy as possible. Visit the RAM - Random Access Memory - What it is and how to buy the right type article on this website for more information on it.

Click here! to go to the full list of hardware and software problems dealt with on this website


RAM diagnostic tools/utilities

The following free utilities can test your system's RAM, which must be operating 100% all of the time or serious data corruption and/or system failures (that can be very difficult to track down) will occur. Note that they can take a lengthy time or a very long time to go through their various tests. As long as you can boot the computer from a floppy disk or CD, if you copy the utilities to such a disc/disk, you can run the diagnostic tests in Windows XP.

Microsoft Windows Memory Diagnostic tool - with full instructions on how to use it from a boot disc. -

http://oca.microsoft.com/en/windiag.asp

Memtest86 - latest version - http://www.memtest.org/ and http://www.memtest86.com/

The Windows Memory Diagnostic tool is part of the Administrative Tools suite within Windows Vista and Windows 7.

How do I know if my computer has a memory problem? [Windows Vista] -

"Usually, Windows [Vista] automatically detects possible problems with your computerís memory and displays a notification that asks if you want to run the Memory Diagnostics Tool." -

http://windows.microsoft.com/en-PH/windows-vista/How-do-I-know-if-my-computer-has-a-memory-problem

Diagnosing memory problems on your computer [Win7] -

"If Windows detects possible problems with your computerís memory, it will prompt you to run the Memory Diagnostics Tool."

http://windows.microsoft.com/is-IS/windows7/Diagnosing-memory-problems-on-your-computer


RAM MEMORY PROBLEMS AND SOLUTIONS

Click the relevant link below to go to that Q&A article. Use your browser's Back button to backtrack

1. - Articles on RAM memory errors and problems in the Microsoft Knowledge Base

2. - Which number on this laptop SODIMM RAM memory module identifies it so that I can order an identical module to run in dual-channel mode?

3. - Due to high RAM memory use I have to restart my PC

4. - Desktop PC suffers a series of Blue Screens of Death (BSOD) followed by a failure to turn on

5. - HP G62 laptop with 3GB of RAM memory (1GB and 2GB modules) shows 3GB of memory installed but only 763MB usable

6. - Where to get low density DDR2 RAM [Computer-forum link] - http://community.plus.net/forum/index.php/topic,91830.0.html

7. - Windows 7 Resource Monitor reports that Windows Media Player Network Sharing Service - wmpnetwk.exe - is eating RAM memory

8. - My desktop PC's DDR2-1066 (PC2-8500) RAM memory is running slowly - at the speed of slower DDR2-800 (PC2-6400) memory

9. - My computer running the 64-bit version Windows 7 Home Premium isn't using all its 4GB RAM memory

10. - I have a PC with Windows XP Professional SP3/Windows Vista and 4 GB of RAM but it only detects 3GB and the 500GB hard drive only shows as 466GB

11. - The specifications of my Windows Vista computer says that it has 4GB of RAM memory, but Vista itself and SiSoftware Sandra report that it has only 3GB

12. - Faulty RAM memory/motherboard/power supply/overheating processor: My PC/computer constantly reboots 10 to 20 minutes after startup/being switched on

13. - Can I install 4GB of RAM memory in my PC/computer?

14. - Why is 1GB of PC6400 (800MHz)/DDR2-800 DDR2 RAM memory reported by CPU-Z as running at only 333MHz?

15. - The RAM memory requirements of Windows Vista and Windows 7: How much DDR/DDR2/DDR3 RAM memory does Windows Vista and Windows 7 need to run optimally?

16. - Only three of the four 1GB DDR2-667 RAM memory modules (sticks) installed in my PC's motherboard work AND The amount of DDR2 memory has halved instead of doubled after I installed a 1GB module with two 512MB modules

17. - When I install one module of 2GB DDR2 RAM memory in my PC's GIGABYTE GA-MA78GM-S2H motherboard the system boots, but with two modules it won't boot

18. - Should I install a single RAM memory module running in single-channel mode or a matching pair running in dual-channel mode on my PC's motherboard?

19. - My PC/computer doesn't recognise [US: recognize] the additional RAM memory/memory upgrade I installed

20. - If you suspect you have faulty RAM memory, try using one of these free RAM diagnostic utilities

21. - How to identify the size of RAM memory modules

22. - I am confused by the types of DDR RAM memory. Which type of DDR RAM memory should I buy?

23. - Some Crucial RAM memory questions

24. - Reported RAM memory does not match installed memory - Windows95/98

25. - Installing more RAM memory on a motherboard in a Windows 98 system causes problems

26. - Why does a double-sided DDR RAM memory module work in one DIMM slot but not in the other two DIMM slots on my motherboard?

27. - My Windows XP computer doesn't recognise 1GB of RAM memory when 4GBs are installed

28. - Which type of RAM memory do I have to install to upgrade my PC?

29. - A RAM memory upgrade won't work in my laptop computer

30. - Advice on how to upgrade the RAM memory for a PC with an Asus A7A266 Socket A motherboard required

Click here! to go to the full list of hardware and software problems dealt with on this website


Which number on this laptop SODIMM RAM memory module identifies it so that I can order an identical module to run in dual-channel mode?

Problem

I have read your article on RAM memory. However, I would still like some more info, if you do not mind? If you take a look at my attached photo, can you please tell which part of the two long numbers I should be taking into consideration when looking to add RAM Ė not replace RAM? I understand that for everything to run smoothly it is vital that the two modules match. I would like to buy one to match my existing one, rather than buy a pair, replacing the one already installed.

A 4GB DDR3 laptop SODIMM memory module showing the part number

Answer

This is the part number on the laptop SODIMM module - HMT351S6BFR8C-H9.

Enter it in a search engine and you'll be able to find plenty of suppliers. I saw some available on eBay. Just remember that you need a 64-bit version of Windows Vista / 7 / 8.1 in order to be able to use more than 4GB. A 32-bit version of Windows cannot use more than 4GB. If you don't know, enter the following search query into a search engine: 32 bit or 64 bit windows - adding your version of Windows.

You only need matching modules if you want to run the memory in dual-channel mode, which is slightly faster. If you visit crucial.com and search for your model of laptop, using the Memory Advisor will tell you which capacities of memory modules can be used on it.

Read this:

Matching Modules for Dual-Channel -

http://www.tomshardware.co.uk/answers/id-1730703/matching-modules-dual-channel.html


Due to high RAM memory use I have to restart my PC

Problem

In the Windows 8 Task Manager, svchost.exe is being shown as using around 135MB of RAM memory itself, which seems highly excessive to me. No other system file uses anything like that much memory. A huge 12GB of memory is installed in a Windows 8 64-bit system and it is causing 90% or more of it to be used, which is completely out of order. I have to restart the computer in order to get back to normal, but the problem returns as soon as I go online. Do you have any idea what's going on here and how it can be put right?

Answer

After a fairly long investigation, the cause of this turned out to be the V9 Portal Site and en.v9.com, which hijacks the browser, in this case Google's Chrome, but it could have been any other rogue software of the same kind. It is installed with free software and changes the default home page to en.v9.com and default search engine to search.v9.com. This is not unusual. The web user probably didn't disable an option that makes the changes while installing the software. You should always take care when installing free software because most of it is installs something you don't want unless you choose to disable the option to do so. Even the Adobe Flash Player update provides an enabled setting that installs Google's Chrome browser or McAfee security software unless the user disables it. This particular rogue software is malware because it goes further by changing random Windows shortcuts on your desktop and your Windows Start Menu so that they show ads and sponsored links in search results and may collect the user's web-search queries.

Here is a website that provides instructions on how to remove the infection should the solution provided below not be available due to the fact that System Restore was disabled, doesn't work or hasn't got a restore point that preadates the infection:

Remove V9 Portal Site and en.v9.com (Removal Guide) -

http://malwaretips.com/bogs/v9-portal-site-removal/

There is an easier way that works most of the time. If you suddenly find yourself having a problem like this one, which is a common occurrence due to the fact that so much free software can install rogue or unwanted software if the user fails to notice an enabled option that allows this to happen, restoring a System Restore restore point that predated it will make Windows restore itself to the state it was in on that date, removing any software that was installed after that date, thereby fixing the problem. The restore point has to predate the infection because restore points can restore infections if they were created while the infection was installed.

Visit the following page on this website for information on how to use System Restore in Windows XP/Vista/Windows 7 & 8:

http://www.pcbuyerbeware.co.uk/Recovering-Windows-XP-Using-System-Restore.htm


Desktop PC suffers a series of Blue Screens of Death (BSOD) followed by a failure to turn on

Problem

After not being in use for about a month, my desktop PC underwent a series of blue screen of death crashes and then failed to turn on. Its power LED lights up on the motherboard when I press the Start button, makes no beeping sounds and nothing appears on the monitor. After a while, it tries to restart itself without success. I can't get it to open the BIOS. I took all of the adapter cards and two 1GB RAM modules out, cleaned their connectors and blew the dust out with a can of compressed air, but it still refused to turn on. A friend tested the hard drive by installing it in his PC and it worked properly. I can't take his PC apart to swap out his PC's components with mine, so how else can I find out if the motherboard, the RAM, the processor or the power supply are the cause of the problem?

Answer

You say that an LED lights up on the motherboard when you switch the PC on but that there are no beeps (beep code that can be translated to reveal which component is at fault).

A desktop PC has to have a case speaker for BIOS beep codes to be heard, which most PCs no longer have, but you may get warning codes provided by an LED display on the motherboard itself or on an LED display at the back of the case. The codes are provided in the motherboard's user manual or may be provided online. Most motherboard manufacturers provide user manuals for their boards in the PDF format from their websites. A web search for bios beep codes should provide you with the information you need to translate the message being sent by a standard BIOS. If you know the make of your PC's BIOS, include it in the search query. The most common makes of BIOS are AMI and Award.

This is certainly a hardware-related problem, but you can test the computer by creating a Linux boot disc that boots the system from a CD or DVD, such as the one provided by Ubuntu from ubuntu.com. If the PC can be run from the boot disc then it's a software problem (a hardware problem if it doesn't work). You use disc-burning software to burn the downloaded Ubuntu ISO file to a disc. Note that to boot the system using a boot disc, the system BIOS has to have the boot-order settings of devices set so that the CD/DVD drive is set as the first boot device. Windows 7 provides disc-burning software, but there are many excellent free third-party tools, such as CDBurnerXP Pro from cdburnerxp.se. Note that Windows 8 does not provide a disc-burning tool.

The order of components that can be responsible for this kind of failure are: 1. RAM memory 2. power supply failure. 3. motherboard failure. 4. processor fault. 5 graphics-card problem. The boot hard drive is not required to be able to enter the BIOS, because it uses its own flash memory and doesn't even require using system RAM memory. In any case, you say that your hard drive has been tested and found to be working.

Looking at the symptoms, I would say that it's most likely to be a problem with the RAM memory. If any of the other components are responsible you can only find out by swapping them out with components known to be working or get a computer repair shop to find out which component is responsible. I have come across a few PCs with those tell-tale signs and the memory is usually to blame.

Look at the motherboard user manual to find out how the two memory modules can be installed in the DIMM memory slots on the motherboard and install them in all of the available configurations - singly and together. This, of course, requires opening the PC's case to access its motherboard. Not usually a difficult thing to do, but some cases require more than removing four screws at the back of the case to set the side panels free. For example, access might require removing the whole front section of the case to allow the side panels to be removed. Most brand-name cases have user manuals provided by their manufacturers and most brand-name PCs come with a user manual that provides instructions on how to open the case.

A memory slot might have become faulty as well as a module. Some motherboards require the modules to be installed in specific banks and others don't mind which banks are occupied or left empty, but most of them only allow specific configurations with the first bank, which is numbered as such, having to be filled. To run the memory in a dual-channel configuration that runs two modules as if they are one module, for example, might require installing the modules in specific slots that can be colour-coded. You might find that using one module alone in the first bank works while the other module doesn't (has become faulty) in the same slot. Experiment until you are sure that both memory modules are working or that one or both of them need to be replaced. Also remember that the slots can become faulty, so if a module doesn't work in a slot, try the other module in it. If both don't work but work in another slot then you know that the slot has become faulty not the memory.

The person who reported this problem subsequently reported that the problem was cause by one of his memory modules having become faulty.


HP G62 laptop with 3GB of RAM memory (1GB and 2GB modules) shows 3GB of memory installed but only 763MB usable

Problem

My HP G62 laptop PC runs Windows 7 Home Premium. After I started using Photoshop Elements 10, it slowed down very noticeably, so I had a look in System Properties (enter the word system in the Start =>Search... box and click on the System link under the Control Panel heading). It shows 3GB of RAM memory installed but only 763MB [about three quarters of a gigabyte] usable. The Windows and HP memory-diagnostic tools find no fault with either of the modules. When I press the Ctrl+Alt+Del key combination and choose to open the Task Manager, when no programs are running, the Performance tab shows the Physical Memory around 760MB with the graph running at the very top. When I click on the Resource Monitor button, the Memory tab shows 635MB in use and 2310Mb hardware reserved. I tried removing the 1GB module. On startup, only the power light lit up - no boot. I moved the 2GB module to DIMM slot 1 where the 1GB module was and started up. The Caps Lock key's LED came on but the system did not boot. When booting with the 1GB module it still shows 763Mb available, which is probably about right.

Answer

My most problematic self-built desktop PC wouldn't boot and I couldn't even get into the BIOS, but the processor cooler's fan spun. I used floppy disks to test the memory with a few reliable memory diagnostic tools on them, which all passed the memory as being fit for purpose, so I swapped the power supply, the graphics card and the motherboard with components that worked in other PCs, but without success. I tested the processor in another PC. That left only the memory. At that time, I didn't have any DDR3 memory to swap out, so I used the Crucial Memory Advisor on crucial.com/uk to tell me which memory configurations were supported by the make/model of motherboard, ordered the memory I wanted and the system booted up from the Windows installation disc immediately after it was installed. What a lovely feeling it is to see a self-built computer boot for the first time. I sent the incompatible memory back to the vendor (not Crucial, the vendor that supplied all of the other components). Therefore, memory can pass several tests and still not function.

Your 2GB memory module is amost certainly faulty and should be replaced, or, better still, get the best configuration of memory modules that the laptop supports.

You didn't supply the exact model number for the HP laptop, but the G62 series of laptops support dual-channel memory configurations, so better performance will be achieved with an identical matching pair of modules working in dual-channel mode.

Note that the DIMM memory slots are usually colour-coded to indicate which slots should be filled in order to run the memory modules in dual-channel mode. For example, the first and third of four slots may be coloured blue with the second and fourth slots coloured white. You would install two identical-capacity memory modules in the blue slots (first and third) first and another two identical-capacity modules in the other two slots in order to have them working in dual-channel mode. If you have modules with odd capacities (e.g., 2GB and 1GB), you would install them in the first two slots, because non-identical modules cannot function in dual-channel mode. The motherboard's user manual provides the information about which capacities of module can be installed in the DIMM slots and in which configurations. If you don't have a manual, download one from the motherboard manufacturer's website (msi.com, gigabyte.com, asus.com, etc.) It is usually in the PDF format, which requires a PDF reader such as Foxit. If you want to find out the make/model of the motherboard without opening the case in order to determine which website to visit, you can use CPU-Z from cpuid.com.

I would buy a 4GB upgrade kit (2x 2GB) and keep the 1GB for a emergency or sell it on eBay. If you have Windows 7 Home Premium 64-bit version installed, or intend to install it, a 6GB or 8GB kit can all be used and should future-proof the laptop for several years. A 32-bit version of Windows Vista, Windows 7 or Windows 8 can only use approximately 3.5GB, so there is little point in installing any more than 4GB on a 32-bit system.


I have a PC with Windows XP Professional SP3/Windows Vista and 4 GB of RAM but it only detects 3GB and the 500GB hard drive only shows as 466GB

Question

I have a PC with Windows XP Pro SP3 and 4GB of RAM, but it only detects 3.5GB. The PC has a 500GB hard drive, but Windows XP only recognises it as a 466GB drive. Have I been short-changed in memory and disk capacity?

Answer

The 32-bit version of Windows XP Professional and the 32-bit versions of Windows Vista and Windows 7 can only use only about 3.5GB of RAM.

Under System in the Control Panel (System Properties), Windows XP only shows the amount of memory installed; Windows Vista and Windows 7 show the amount of RAM installed and the amount of usable memory.

The 64-bit version of Windows XP Professional and the 64-bit versions of Windows Vista can use very much more - up to 128GB. However, note that to run a 64-bit operating system, a computer must have a 64-bit processor, which all relatively new desktop and laptop computers have had since about 2005. A 64-bit version of Windows XP/Vista must have 64-bit device drivers for its hardware.

If 4GB of memory is installed, 3.5GB can be used by Windows, but the remaining half a gigabyte (0.5GB) is not used by the system. However, if you have an onboard graphics chip built into the motherboard instead of a plug-in graphics card, if it also doesn't have its own dedicated memory built into the motherboard, a small part of the installed RAM (usually between 128MB to 256MB) is reserved for the graphics (by a setting in the BIOS setup program the amount of which can often, but not always, be set in the BIOS), and the memory shown under Start => Control Panel => System => System Properties reflects this by deducting it. (System is also available in the Control Panel in Windows Vista.) So, if you have 4GB of memory installed, Windows XP Pro (32-bit version) recognises and can use 3.5GB, but the graphics card will be able to use the remaining 500MB (0.5GB). If an onboard graphics chip (built into the motherboard) is allocated 256MB of system memory in the BIOS, that much will be reserved for it use, but if more system RAM memory than that is available, the graphics chip can use it if it requires it.

Note that if you want to install a dedicated graphics card in a motherboard that has an onboard graphics chip, you usually have to disable the onboard graphics chip in the BIOS first. An alternative method is to enable/disable the onboard graphics chip by using a jumper setting on the motherboard, but this method is seldom used nowadays.

With regard to the 500GB hard disk drive, the hard-drive manufacturers and software developers don't agree on the definition of a GB (or a MB for that matter). Obviously, it makes hard drives look bigger if 1GB = 1000MB instead of the real mathematical figure of 1024MB, so the drive manufacturers don't want to use the real figure.

Note that the 64-bit version of Windows XP Professional (and the 64-bit versions of Windows Vista) can use 128GB of RAM. (Windows XP Home Edition is only available as a 32-bit version.) Software developers, including Microsoft, use 1GB = 1,024MB, which is the correct figure, but for the hard-drive manufacturers 1GB = 1,000MB, which is 24MB less per GB, so you would see some difference between the manufacturer's figures and those reported by Windows. According to the drive manufacturers, a 500GB drive has 500 x 1000 = 500,000 megabytes (MB), but Windows correctly recognises 1,024MB as a gigabyte (GB), so it will report an empty drive as 500,000/1,024 = 488GB. However, Windows XP uses the NTFS file system, which takes up space, and which Windows does not count, so a drive with Windows installed on it would be reported as a 466GB drive.


The specifications of my Windows Vista computer says that it has 4GB of RAM memory, but Vista itself and SiSoftware Sandra report that it has only 3GB

Question

I need to know how to establish how much RAM memory my desktop PC (that is running Windows Vista Home Premium edition) has. Its user manual says that it has 4GB, but both SiSoftware Sandra and Vista itself in System Properties [Start => right-click Computer => Properties => General tab] say that it has 3GB. Which of them is correct?

Answer

Windows XP shows the amount of RAM memory it can use; Windows Vista shows the amount of RAM installed. Therefore, since both System Properties and Sandra show 3GB, that is probably how much memory is installed. You can make absolutely sure by checking how much memory is installed in each memory slot by using the free CPU-Z utility from cpuid.com. Look under its Memory and SPD tabs for that information.

However, you should be aware of the following information. Your PC must be running the 32-bit version of Vista Home Premium. (64-bit versions are available for most of the different versions of Vista and they can access a huge amount of RAM memory - up to 128GB.) Due to the limitations imposed by 32-bit software, the 32-bit versions of Windows XP/Vista (or any other 32-bit operating system) can only access a maximum of about 3.5GB of RAM.

The following Microsoft Knowledge Base article explains why that is the case with Windows Vista and under which circumstances a 32-bit version of Vista will allow the system to acknowledge and support 4GB.

The system memory that is reported in the System Information dialog box in [a 32-bit version of] Windows Vista is less than you expect if 4 GB of RAM is installed - http://support.microsoft.com/kb/929605


Faulty RAM memory/motherboard/power supply/overheating processor: My PC/computer constantly reboots 10 to 20 minutes after startup/being switched on

Problem

I have a problem with my desktop PC (Windows XP SP3, AMD Athlon 64 X2 3800+ dual-core processor, 1GB of RAM, 250GB hard disk drive, CD/DVD writer) and I hope that you can tell me why it reboots 10 to 20 minutes after it has been switched on. I've changed the RAM memory and reformatted the hard disk drive, but without success. Could this be a hardware issue? Please list all of the possible causes of this problem and all of the possible solutions.

Answer

The following two links provide comprehensive cover of PC rebooting problems of that kind:

Windows XP Shut Down and Automatic Reboot Problems - http://www.microsoft.com/windowsxp/using/helpandsupport/learnmore/...

System Continually Reboots - http://www.5starsupport.com/xp-faq/1-92.htm

You have changed the RAM memory, but it is important that any new RAM module(s) are fully compatible with both the motherboard and/or any other RAM module(s) already installed in the system (new RAM could also be bad). Your PC is elderly so note that there can be jumpers on older motherboards that need to be set for specific RAM configurations. Consult your motherboard's manual (downloadable in the PDF format from its manufacture's site for your PC's make/model of motherboard), or the PC manufacturer's website for specific instructions and compatibility requirements.

If you don't know the make and model of the motherboard installed in your computer, here is a good free utility - Belarc Advisor - that creates an analysis of the hardware and software on a personal computer. Look under FREE DOWNLOAD from belarc.com. Another free utility that also provides detailed information on the memory itself is CPU-Z from cpuid.com.

It is advisable to use a good memory-test program to check your new and old RAM. Here are two:

http://hcidesign.com/memtest/ and http://www.memtest86.com/

You can use the UK and US Crucial Memory Advisor provided from crucial.com (US) and crucial.com/uk (UK) to determine the correct RAM and capacity for your specific make and model computer and/or motherboard.

The PC's motherboard could have developed faults. For instance, malfunctioning capacitors on a motherboard can be responsible for a wide range of issues. It is possible for capacitors to fail due to a bad power source. If you see one or more capacitors (the cylindrical components that are soldered to and stick up from the motherboard) that are leaking substances, you have to replace the motherboard.

Some motherboard manufactures provide fault-testing software, so conduct a search of your PC's motherboard manufacturer's site for free software.

The computer may be overheating. Circuitry in the motherboard could be making the PC reboot if that is the case. You may have moved the computer somewhere where it isn't getting sufficient air to keep cool, or its internal extractor fan(s) might have stopped working, or there could be a build up of dust inside the case or within the power supply unit. You can remove dust in the case and the power supply by making use of a can of compressed air that can be purchased from good computer stores. Note well that you must never open the power supply unit to clean it because it can retain a lethal charge long after the PC has been switched off. The heatsink and fan unit over the processor could be failing and not keeping the processor cool. If the processor's cooling unit fails, then relatively recent PCs will just freeze (the processor will stop working) to protect it, not reboot. A processor's cooling unit has a limited life and should be replaced every so often depending on how long you keep the PC running. If it is left on 24/7 or for many hours a day, you should relace the cooling unit every 18 months, but if you only have the PC on while you work with it for a few hours a day, the cooling unit will probably last as long as the PC itself. You can open the case, which usually involves removing the screws that keep a side panel in place and then turn the PC on. You can then watch the extractor fan(s) and the processor's cooling unit to make sure that it is working consistently. Make sure that it is fitted tightly over the processor.

The PC's power supply unit (PSU) may be failing. If that is the case, it has to be replaced. With an elderly PC such as yours, make sure that you buy the correct type of PSU for the PC's motherboard. Your PC's motherboard probably uses a power supply that has a 20-pin connector. The latest motherboards use a 24-pin connector. If your PC's motherboard uses the older 20-pin connector, make sure that you buy a power supply that provides both types of connector, because you can no longer buy new power supplies that only have the 20-pin connector.

Find out if your PC is overheating with this free utility (which doesn't work with all motherboards, because the author stopped updating it in 2004, but it may still work with your PC's motherboard):

Motherboard Monitor - http://www.pcworld.com/downloads/file_description/0,fid,7309,00.asp

If you installed a new application or updated one or more a device drivers just before the reboots started occurring, that may be the cause of the problem. If that is the case, try uninstalling the program or use the Roll Back Driver feature, or use System Restore to roll back your system to a known good configuration. You should also make sure that Windows XP is full updated. The free Belarc Advisor utility from belarc.com tells you if there are missing updates.

System Continually Reboots - http://www.5starsupport.com/xp-faq/1-92.htm - provides information on overheating (cleaning the PC internally) and what to do to find out if the PC's power supply is going bad.


Can I install 4GB of RAM memory in my PC/computer?

Question

I would like to install 4GB of RAM memory in my gaming desktop PC, but I've read that Windows XP and Windows Vista won't recognise all of it. Is this true, because I have also read that 4GB is the best amount or memory for Windows Vista. My PC runs Windows Vista Home Premium.

Answer

You can install up to 4GB of memory in a 32-bit version of Windows XP or Windows Vista, but only around 3.5GB can be used. Any more than that in a 32-bit version of Windows will have a negative effect and actually reduce performance. The 64-bit versions of Windows XP and Vista can use more RAM than current motherboards support - in most cases up to 128GB. You should install 4GB in a gaming PC for the best performance.

A computer running Windows XP Home Edition that doesn't run memory-hungry applications, such as video-editing software, should have minimum of 512MB of RAM memory to run comfortably, but it runs best on 1GB of memory. Such a computer will run ordinary office applications, etc., with 256MB of memory, but slowly. Motherboard user manuals recommend that the 32-bit versions of Windows XP Home and Professional Editions should not have more than 3GB of memory installed, because they don't support more than that amount of memory. The 64-bit version of Windows XP Professional and the 64-bit versions of Windows Vista support up to 128GB of memory, which cannot be installed on current motherboards because only 8GB modules are currently available, with 16GB modules on the way, and even motherboards that support Intel Core i7 quad-core processors only have six DIMM memory slots.

Most of the versions of Windows Vista require more RAM memory to run optimally (on a computer that doesn't use memory-hungry applications) than Windows XP. A video-editing application is an example of memory-intensive software. Only Windows Vista Home Basic has a recommended minimum amount of memory of 512MB, which is the same minimal amount recommended for Windows XP. Windows Vista Home Premium, the most popular version, and Windows Vista Ultimate require a minimum of 1GB (1024MB) of memory, which is twice the minimal amount of memory recommended to run Windows XP. You should not install more than 4GB of memory in a PC running a 32-bit version of Windows Vista.

If you want to install 4GB or more of RAM, the computer must have a 64-bit processor, which almost all new computers now have. You can find out if a particular Intel or AMD processor is 32-bit or 64-bit from the following page:

Desktop CPU Comparison Guide -

http://www.techarp.com/showarticle.aspx?artno=337&pgno=0

The computer must also be running a 64-bit operating system, which could be the latest versions of Linux, or the 64-bit versions of Windows XP Professional (XP Home Edition only comes as a 32-bit version), or the 64-bit versions of Windows Vista, which are:

Windows Vista Enterprise 64-bit edition • Windows Vista Home Basic 64-bit edition • Windows Vista Home Premium 64-bit edition • Windows Vista Ultimate 64-bit edition • Windows Vista Business 64-bit edition

64-bit Editions of Windows Vista - http://www.microsoft.com/windows/products/...

Note well that the 32-bit versions of Windows Vista will recognise less than 4GB of memory unless the computer meets certain requirements.

Read this MS Knowledge Base article for more information:

The system memory that is reported in the System Information dialog box in Windows Vista is less than you expect if 4 GB of RAM is installed - http://support.microsoft.com/kb/929605

Read this Q&A on this page for more information on Vista's RAM requirements: The memory requirements of Windows Vista: How much RAM memory does Windows Vista really need to run optimally?

Buying a new PC? 'Windows Vista Capable' barely hits the mark - IBM'er says Vista's RAM sweet spot is 4GB -

http://www.computerworld.com/action/...articleId=9011523•intsrc=hm_list


Why is 1GB of PC6400/DDR2-800(800MHz) DDR2 RAM memory reported by CPU-Z as running at only 333MHz?

Problem

My computer has an Intel Core 2 Duo dual-core processor and runs Windows Vista Home Premium. It has 1GB of PC6400/DDR2-800 (800MHz) DDR2 RAM memory. But when I use the CPU-Z utility from cpuid.com, under the Memory tab, it reports the memory as running at only 333MHz. Why is that the case when it is 800MHz memory?

Answer

DDR stands for double data rate. DDR/DDR2/DDR3 memory works by doubling the memory speed to get to its true speed. Therefore, if CPU-Z reports a memory speed/frequency of 333MHz, you have to double it to find out what its real speed is. In your case that is 667MHz, because 666MHz is not used for memory specifications. That is slower than the 800MHz that the memory your computer has is supposed to be running at.

That could be because the computer's motherboard may not support 800MHz DDR2 memory, even though it is installed. If that is the case, it is running the memory as fast as it can. You can find out which memory the motherboard supports in its user manual, or the user manual that came with a brand-name PC (Dell, HP, etc.). If you don't have a manual, you can also use CPU-Z to identify the make/model of the motherboard and then use the web search engine of your choice to locate the manufacturer's website, from which you can download a copy in the PDF format.

It could also be due to a problem with the motherboard's BIOS setup program, which uses Serial Presence Detect (SPD) to detect the memory. If it reads the information incorrectly, it can run the memory too slowly. If that is the case, you can put it right by starting the computer so that it enters the BIOS. Visit the BIOS section of this website if you don't know how to do that.

Open the page in the BIOS that sets the memory timings. The settings are usually on the Advanced Chipset Setup page. Set the memory speed to DDR2-800MHz if it is available, or to 400MHz if you have to enter the memory speed/frequency manually. Use the option to save the change when you exit the BIOS. You may have to enter Y when it asks if you want to save the changes. The computer should start up normally when it comes out of the BIOS. Back in Windows Vista, you can check the speed with CPU-Z.


The RAM memory requirements of Windows Vista and Windows 7: How much DDR2/DDR3 RAM memory does Windows Vista and Windows 7 need to run optimally?

Question

I have a new laptop/notebook computer with 1GB of DDR2 RAM memory that uses 128MB of it to power its built-in graphics. In other words, 128MB of system memory is used for the graphics instead of the graphics chip having its own dedicated memory. The laptop runs the 32-bit version of Windows XP Pro very well. It came with a free upgrade to Windows Vista Business edition, which I have yet to install. I was going to install it on a separate partition. I am worried now about installing Vista, because I have read the following article, and my laptop only has one free memory slot for a 1GB DDR2 memory module.

Buying a new PC? 'Windows Vista Capable' barely hits the mark - IBM'er says Vista's RAM sweet spot is 4GB -

http://www.computerworld.com/action/...

In other words, the machine's maximum supported memory is 2GB and it has a Windows Vista Capable sticker on it. I have discovered that a computer has to be called Windows Vista Ready if it supports all of the requirements of the highest versions of Windows Vista. In other words, my new laptop will be able to run Windows Vista, but not unreservedly. If it needs 4GB of memory to run optimally, as that article says, then it never will be able to do so, because the maximum supported amount of memory is 2GB (one 1GB module in each of the two memory slots), and that cannot be changed.

Also, I have read that the versions of Windows 7 [due out in October 2009 to the general public] can be run comfortably on a relatively low-specification netbook computer, whereas Windows Vista cannot due to its higher hardware specifications. If that is the case, will Windows 7 run better than Vista on less memory? Because if it can, then I will skip installing Vista and get Windows 7 instead.

Answer

As usual, Microsoft's recommended minimum amount of RAM memory for the different versions of Windows Vista has caused quite a bit of controversy. Ever since Windows 95, Microsoft's "minimum" hardware requirements mean the least amount of hardware that is required to get a particular version of Windows functioning.

To run any version of Windows Vista, Microsoft says that those minimum hardware requirements are an 800MHz processor, 512MB of RAM, and a graphics card that is at least compatible with DirectX 9. Needless to say, it won't be a pleasant experience running Vista on that low-specification hardware.

With regard to Windows 7, Microsoft will not be providing a version of Vista for netbook computers, most of which currently run on Windows XP Home Edition, because Windows 7 can run a netbook computer almost as well as Windows XP. According to early tests this is because Windows 7 performs better than Windows Vista on the same hardware. This must be the case or else Microsoft would be making a netbook version of Windows 7 available, which it is not going to do. So, if I were you, I would skip installing Vista and go for Windows 7 instead, which has to be installed on a separate partition, because Microsoft has confirmed that an upgrade licence for Windows 7 from Windows XP will be available in the USA, but, unfortunately, users will have to wipe their hard drive and perform a clean installation, which means that an in-place upgrade is not possible. However, the upgrade licence no doubt be cheaper than the full licence. Initially, none of the upgrade versions will be available in Europe.

In the USA, you will be able to buy upgrade versions of Windows 7 if you are upgrading from Windows Vista and therefore be able to perform an in-place upgrade as well as a clean installation. However, in Europe, the upgrade versions will not be available until Microsoft can create setup programs for them that removes the Internet Explorer web browser from Vista, because the EU has made it illegal for Microsoft to have Internet Explorer installed as part of Windows. Windows 7 in Europe will not install Internet Explorer. It will come on a separate DVD and its installation will be optional. Because of this, Microsoft will be selling the full versions of Windows 7 at the same price as the upgrade versions would have been sold for in Europe (including the UK) until upgrade versions are available that can remove Internet Explorer and the install Windows 7.

You shouldn't have any problem instaling Windows 7 on a computer that can run Vista (a "Vista Capable" or a "Vista Ready" computer). However, I would also upgrade the memory to 2GB for the best performance.

The minimum hardware requirements of the final versions of Windows 7 are likely to be the following:

1 GHz or faster 32-bit (x86) or 64-bit (x64) processor
1 GB of RAM (32-bit versions)/2 GB of RAM (64-bit versions)
16 GB of available disk space (32-bit versions)/20 GB (64-bit versions)
DirectX 9 graphics device with Windows Display Driver Model 1.0 or higher driver

The minimum hardware requirements of the versions of Windows Vista are:

1 GHz or faster 32-bit (x86) or 64-bit (x64) processor
1 GB of RAM (32-bit versions)/2 GB of RAM (64-bit versions)
16 GB of available disk space (32-bit versions)/20 GB (64-bit versions)
DirectX 9 graphics device with Windows Display Driver Model 1.0 or higher driver

Windows Vista would run on a desktop or laptop computer with the hardware listed above, but it won't be an enjoyable experience - especially if it is 64-bit version of Windows Vista. In fact, if you have a PC with that sort of hardware, you should only use the Windows Vista Home Basic version.

Most of the versions of Windows Vista require more RAM memory to run optimally on a computer that doesn't use memory-hungry applications than Windows XP. A video-editing application is an example of memory-intensive software. Only Windows Vista Home Basic has a recommended minimum amount of memory of 512MB, which is the same minimum amount recommended for Windows XP. Windows Vista Home Premium, the most popular version and Windows Vista Ultimate require a minimum of 1GB (1024MB) of memory, which is twice the amount of memory recommended to run Windows XP. Read the information on the RAM pages of this site to find out if you should buy memory for use in single-channel or dual-channel modes. [Note that Intel's new Core i7 quad-core processors run on Socket LGA1366 motherboards that have six memory slots for two sets of three identical DIMM DDR3 memory modules to be able to run in triple-channel mode.]

The new key features of Vista, such as the new AeroGlass/Flip 3D interface won't run of the minimum hardware requirements. Read the information provided on the Using Windows Vista section of this site for more information on Vista's new features and the hardware that is required to run them.

Graphics Hardware and Drivers for Windows Vista - http://www.microsoft.com/whdc/device/display/graphics-reqs.mspx

Microsoft recommends that a Windows Vista Ready computer should have a graphics card with 128MB of dedicated video memory (not an integrated graphics chip on the PC's motherboard that uses 128MB of system memory) that supports DirectX 9.0 and Pixel Shader 2. A system like this should allow all of the key components of Windows Vista to run. Nevertheless, the "recommended" hardware requirements are still not equivalent to an "optimal" system setup.

Many experts recommend that Vista should run on at least 2GB of RAM, which is widely considered as being the optimal amount of memory to run Windows XP on. However, Windows Vista (from the Vista Home Premium version up) is a bigger and more complex operating system than even Windows XP Professional Edition, so it will not run as well on 2GB of memory as Windows XP does. However, most users will probably find that the performance of any version of Vista will be perfectly acceptable with that amount of memory.

All of the 32-bit versions of Vista support up to 4GB of RAM, of which about 3.5GB can be utilised. For your information, the 64-bit versions support more than that. Note that if you have a 64-bit version of Vista, its memory requirements are twice that of 32-bit versions. But do the 32-bit versions of Vista really need 4GB of memory? - No. a 32-bit version of Vista runs in a limited way on as little as 512MB of memory, passingly well on 1GB, and acceptably well on 2GB. However, to run the 64-bit versions of Vista comfortably, 4GB of RAM are required, which is double the amount required to run Windows XP optimally.

Just bear in mind that you say that your laptop computer runs Windows XP Professional well on 896MB (1024MB minus the 128MB used by the graphics chip), so it will probably run Windows Vista Business edition just as acceptably well on 2GB less 128MB (2048 - 128 = 1920MB).

Also read Can I install 4GB of RAM memory in my computer? on this page.


Only three of the four 1GB DDR2-667 RAM memory modules (sticks) installed in my PC's motherboard work

Problem

I have 4GB of PQI Turbo DDR2-667 SDRAM, (PC2-5300) in 1GB memory modules. I installed it, but all I get are long beeps from the motherboard. When I took out two modules, it boots up fine. When I used three modules, it boots up fine, but when I installed the fourth module, the beeps start again. The PC has an EVGA 680i SLI Socket LGA775 motherboard and an 850W Cooler Master power supply.

Answer

A Socket LGA775 motherboard that has four DIMM memory slots and supports the latest Intel processors will support 4GB of memory, with a 1GB module installed in each slot. You should be able to use about 3.5GB of 4GB of memory in the 32-bit versions of Windows XP and Windows Vista, because a 32-bit operating system cannot use more than that. (The 64-bit versions Windows XP (Windows XP Professional 64-bit only) and Windows Vista support up to a huge 128GB of RAM memory.) Your PC's 850W power supply can easily power that much memory. Therefore, either you have a faulty memory module or your motherboard has a faulty DIMM slot/memory bank.

Your PC's motherboard manual will tell you which capacities of memory can be installed in the memory slots. If you don't have a manual, you should be able to download a copy in the PDF format from its manufacturer's website - http://www.evga.com/. If you have any other motherboard and you don't know the make/model you can use the free CPU-Z utility to identify it and then look up the website by using a search engine.

You should always consult the motherboard manual before installing RAM to find out if a particular configuration of modules is supported. For example, an AMD-based motherboard that supports dual-channel mode might not support using three modules, but will support using one, two or four modules. Alternatively, you can make use of the UK or US Crucial Memory Advisor provided from crucial.com, which provides memory on a motherboard or computer make/model basis.

To find out if you have a faulty module, install each of the modules in the first slot/memory bank of the motherboard, and boot up each time with a different module in the slot. If the system won't boot with one of the modules installed, then it's a faulty module. The first, second, third, and fourth slots/banks will be identified in the motherboard's user manual.

If all of the modules allow the system to boot, then you have a faulty DIMM slot. Consult your motherboard's manual to find out what the different combinations of modules are that can be installed in the slots. By installing different permitted single modules or combinations of modules, you should be able to determine which of the slot's is faulty. You could get three modules to boot, so, if one slot is faulty, it is most probably the fourth slot/bank.


The amount of DDR2 memory has halved instead of doubled after I installed a 1GB module with two 512MB modules

Problem

I had two 512MB sticks of DDR2 SDRAM memory in my computer, making a total of 1GB. I then bought another 1GB stick, installed it in my computer, and now Windows XP not only doesn't recognise the new slot, it only recognises one of the previous slots. So, with the new memory installed, I only have 512MB of memory? Windows XP tells me I have only that, but CPU-Z recognises the full 2048MB (2GB) of memory and each individual slot.

Answer

If you have a user manual for your PC's motherboard, it will tell you which memory configurations can be installed in the board's DIMM slots. It could be that the board doesn't support that memory configuration (two 512MB modules in the first two memory slots/banks and one 1GB module in the third slot/bank).

When installing memory it is always best to use modules of the same size (all 512MB modules, all 1GB modules, etc.) If you want to use the memory in the fastest dual-channel mode, the modules must be installed in matching pairs. Until the arrival of Intel's Core i7 quad-core processors in December 2008, only AMD-based motherboards supported dual-channel mode, because only AMD's processors had an on-board (built-in) memory controller that made doing so possible. However, Intel's Core i7 processors have on onboard memory controller that can work in dual-channel or triple-channel mode. Triple-channel mode requires three identical DDR3 SDRAM modules to be installed, which is why Socket LGA1366 motherboards have six memory slots for two sets of three modules. See the RAM section of this website for more information on this topic.

If the 1GB module is made by a different manufacturer than that of the two 512GB modules, it could be that the motherboard is not compatible with the memory made by the manufacturer of the 1GB module. If so, installing it could possibly put one of the 512MB modules out of action. However, it looks as if the motherboard doesn't support that particular configuration of memory. Your motherboard must support a particular memory configuration for the PC to be able to use it. The fact that CPU-Z recognises all of the memory doesn't matter if the motherboard's BIOS doesn't recognise it. However, because CPU-Z recognises the 1GB module, it is probably not faulty.

I have myself been able to install memory in a faulty memory slot that CPU-Z identifies as being present, but which Windows cannot run.

Try installing the 1GB module in the first slot/bank, which is identified in the motherboard's user manual. If you don't have a motherboard manual, you can use CPU-Z to identify the make/model of the motherboard, and then use a web search engine to discover its website address, from which you should be able to obtain a copy in the PDF format. If the PC boots with the 1GB installed, then you have confirmed that the memory configuration of two 512MB modules and one 1GB module, as you installed it, is not supported by the motherboard. The manual will tell you which memory configurations are supported. There may be a configuration (matching module size and slots) that supports all three modules.

You should always consult the motherboard manual before installing RAM to find out if a particular configuration of modules is supported. For example, an AMD-based motherboard that supports dual-channel mode might not support using three modules, but will support using one, two or four modules. Alternatively, you can make use of the Crucial Memory Advisor provided from crucial.com/uk, which provides memory on a motherboard or computer make/model basis.


When I install one module of 2GB DDR2 RAM memory in my PC's GIGABYTE GA-MA78GM-S2H motherboard the system boots, but with two 2GB modules it won't boot

Problem

I just assembled the following PC: - RAM memory: 4GB (2 x 2GB) DDR2 800 - Processor: AMD Athlon 64 X2 5000+ - Motherboard: GIGABYTE GA-MA78GM-S2H - Hard disk drive: Western Digital Caviar SE16 WD5000AAKS 500GB SATA - Case: Antec New Solution with a NSK3480 380W power supply - Optical drive: Liteon IDE DVD-RW . I attached a Dell 17" VGA CRT monitor to start working on the BIOS, but the screen stays blank and the PC won't boot. All the usual lights are on, I can hear the hard drive spin, the DVD drive door opens and closes, the system fan is on, and the cooler fan is on. The cooler fan even seems to be responding to heat, and I can feel some heat in its exhaust. All the connections seem set properly. However, when I remove one of the 2GB modules, leaving a module in the first bank slot, the system boots. The other module also works on its own, but two sticks won't allow the system to boot.

Answer

Note that with the 32-bit versions of Windows XP and Windows Vista, 4GB of memory can be installed, but the system can only utilise about 3.5GB of it. Only the 64-bit versions can use 4GB and more.

In the memory section of the motherboard manual downloaded from gigabyte.com for the GA-MA78GM-S2H board it says that it is recommended that if two memory modules are installed, they should be installed in the first two (yellow) DIMM memory slots. However, two matching modules can also be installed in the third and fourth red slots. If you install a matching pair (same capacity and type of DDR2 memory in the yellow and red slots, they function in dual-channel mode that doubles their bandwidth. If a single module is installed it should be installed in the first yellow slot. It will obviously only be able to work in single-channel mode, because two matching modules are required for dual-channel-mode operation.

Unless a graphics card is installed, that motherboard uses the graphics chip built into it to provide the graphics. The default screen resolution of the onboard graphics might not be compatible with the old-style CRT monitor, so try changing it to a resolution that the monitor supports. You can do that by right-clicking and empty space of the Windows desktop (in Windows XP/Windows Vista/Windows 7), clicking on Properties in the window that comes up, and then clicking on the Settings button in the Display Properties window.

If that isn't the cause of the problem, then run the motherboard's update software, which should have come with it, or visit gigabyte.com, choose the site for your country (the UK uses the EU site) and look for an update for the BIOS for that model. You should be able to find update software that finds updates for the motherboard's device drivers and BIOS. The BIOS configures the system to run its hardware. Apparently, that model of motherboard shipped with the F3 version of the BIOS, but the F4 version is available.

"GIGABYTE motherboards provide two unique BIOS update tools, Q-Flash and @BIOS. GIGABYTE Q-Flash and @BIOS are easy-to-use and allow you to update the BIOS without the need to enter MS-DOS mode." Instructions on how to use them are provided in the motherboard manual.

You might be advised to alter the memory timings and voltage in the BIOS by advisors in computer forums, but the system should be able to run using its default settings, because it has onboard graphics and, as such, the default memory settings would be conservative. The F3 BIOS was probably written to configure only 2GB of memory, but the F4 update has very probably been updated to configure 4GB and more.

However, if the problem still exists after a BIOS update, if you do some research, you can try tweaking the memory timings and voltages by using the MB Intelligent Tweaker (M.I.T.) in the BIOS. The motherboard manual has a BIOS section. You can download the motherboard manual from gigabyte.com by finding the site for your country and searching for Motherboards under Products and then searching for the GA-MA78GM-S2H board from a drop-down menu. In spite of being a recent product, this board is far down in the list.

If you can't get the system to boot with the make of memory you're using, which you didn't name, try using one of the Crucial Memory Advisors provided from crucial.com to buy 4GB of Crucial memory for that make/model of motherboard. Crucial provides memory on a motherboard and PC make/model basis. If listed for your motherboard, it is guaranteed to work or you get a full refund. Shipping is free for standard delivery.


Should I install a single RAM memory module running in single-channel mode or a matching pair running in dual-channel mode on my PC's motherboard?

Question

I am building a PC using an Asus A8V motherboard that will be running an AMD Athlon 64 x2 dual-core processor. The motherboard has four DIMM memory slots and supports the installation of a single memory module that runs in single-channel mode, or up to two matching pairs of modules that run in dual-channel mode. I want to buy 1GB of Crucial memory, but I need to know which of the following options provides the best performance: to install a single 1GB module or two 512MB matched-pair modules.

Answer

The memory bus is 64 bits wide in the DDR memory that your motherboard supports. With a single 1GB module installed in a single-channel mode DIMM slot, the system would only be able to access 64 bits of memory each time it accesses the memory. However, with two 512MB modules installed in dual-channel mode, in theory, the memory bandwidth (the amount of memory that can be accessed) with each access is doubled. This is because the second 64 bits can be accessed while the first module is waiting to perform its next access. There is a latency between memory accesses by the first module that is used by the second module. Therefore, using a matched pair of modules operating in dual-channel mode optimises the performance of the memory.

The two modules have to be identical and installed in the correct DIMM slots to work in dual-channel mode. According to the table in the motherboard's user manual that can be downloaded from asus.com, your Asus A8V motherboard to run in dual-channel mode two modules have to be installed in the first and third DIMM slots (slots 1 and 3). If you have four modules, you can install the other pair in the raiming slots, but the first and the third slots have to be filled first, you cannot use the second and fourth slots first. On this motherboard, you can only use the third slot if you want to use single-channel mode; otherwise you have to use dual-channel mode. You should always consult the motherboard's manual for an illustrated installation guide and to find out what memory configurations are allowed or not allowed. If you don't have a printed manual, download a manual in the PDF format from the motherboard manufacturer's site for that make and model of board.

If any other reader needs to know how to identify the make/model of a motherboard, you can use the CPU-Z utility that also provides all the information you need on the memory that is installed.

A matched pair of modules are usually sold together in a single package by the memory manufacturers, such as Crucial, but you can also use individual modules of the same type and capacity. A matched pair usually costs more than the cost of buying two identical modules. As long as they have the same specifications (type and capacity) modules purchased individually (not as a matching pair) should work perfectly well in dual-channel mode, but some motherboards can be very finicky about the memory they will use. For that reason, it would probably be best to use a matched pair bought as such that are identical in every specification.

Note well that the PC should have a power supply unit (PSU) of good quality to run memory at the high speeds demanded of the dual-channel mode of operation. For example, an inadequate power supply might be able to run each module on its own, or both of the modules in the single-channel slots if the motherboard supports single-channel mode in more than one slot (which your motherboard does not), but fail to run them in the dual-channel slots due to a lack of ability to deliver sufficient power.

Also note that if you buy a single 1GB module of DDR memory, you should replace it if you want to run two 1GB modules in dual-channel mode at a later date. This is because it is not wise to buy modules of the same memory capacity at different times, because they will probably have different memory timings, and dual-channel mode requires the modules to be identical in capacity and in the timings they use. You should also buy the two new modules from the same manufacturer, because modules made by different manufacturers will probably not have identical memory timings. If you use two 512MB memory modules made by the same manufacturer in the first and third slots (as indicated in the motherboard manual), you can install two 512MB or 2 1GB modules in the two remaining slots (2 & 4), because two slots with identical modules is required to run in dual-channel mode, so the two pairs don't have to be modules of the same capacity; the modules of one of the pairs must be matching.

Note that Intel's Core i7 quad-core processors run on Socket LGA1366 motherboards that have six memory slots that can support memory in dual-channel mode and triple-channel mode. Triple-channel mode uses three identical modules of DDR3 SDRAM memory. You should consult the motherboard's user manual to find out which memory configurations are supported.


My PC/computer doesn't recognise [US: recognize] the additional RAM memory/memory upgrade I installed

Problem

I have an HP Media Center PC that runs an Intel Pentium D 2.8GHz dual-core processor with 1GB of RAM memory in the form of a single module . I installed another 512MB memory stick with the exact same specifications that are required for the PC. However, the PC does not seem to recognise the memory, even though it is installed correctly and the PC turns on and works as it should. Why does the PC not recognise the memory, and is there a way to make the PC recognise it? Please provide me with a checklist of the ways that might solve this problem.

Answer

That PC will use the DDR2 RAM, because that is what the motherboards used to run Intel's Pentium D processor's use.

You should read the user manual that came with the computer or identify the make/model of its motherboard and download a motherboard manual to find out which memory types and capacities and configurations are supported.

If you don't know the make and model of the motherboard installed in your computer, here is a good free utility - Belarc Advisor - that creates an analysis of the hardware and software on a personal computer. Look under FREE DOWNLOAD from belarc.com. Another utility that also provides detailed information on the memory itself is CPU-Z from cpuid.com.

It might be a motherboard that can run both DDR and DDR2 memory in specific memory slots and it is no doubt not possible to install both types at the same time. RAM memory modules are keyed with one or two notches in the connect edge that make it almost impossible (but not completely impossible) to install them in the wrong type of slot. Before you install a module, you just have to examine where the notch or notches is/are on the module and then look at the slot on the motherboard that you want to install it in, which will have a divider that the slot in the module connector edge fits over. That you have seemingly successfully installed the additional memory, means that it is the right type of memory for that slot, but the configuration of a 1GB module and a 512MB module might not be supported in the two slots you installed them in.

Another consideration you should be aware of is that some PC motherboards will run one make of memory and refuse to run or recognise another make, so you should have checked hp.com for information on compatible makes of RAM for that particular model. I have installed one make of RAM in a particular motherboard that made the system refuse to boot. Only the power supply unit and processor's fan worked. Even the BIOS setup program was inaccessible. The memory was not faulty, because I had it tested at a PC repair shop that uses special testing equipment. It just wasn't compatible with that particular motherboard. I then installed another make, (Crucial memory has never failed me) and the system booted up properly.

To find out exactly which type of DDR2 memory should be used, you can make use of the UK or the US Crucial Memory Advisor provided from crucial.com. You use the drop-down menu to locate the make and model of your HP PC, which then takes you to the relevant page on Crucial's site. If the model is listed, all of the sizes and types of memory that are listed can be used and should work if installed properly. Note that there is no need to buy ECC RAM for a PC because it is usually only used on mission-critical systems. Unbuffered, non-ECC memory is perfectly good. Crucial refunds your money if its memory doesn't work in a brand-name PC or motherboard that it provides memory for.

You should note that the memory has to be installed in the correct DIMM slots. You can use DDR2 memory in single or dual-channel modes with AMD Athlon processors, but at the moment Intel motherboards only support single-channel mode because because current Intel processors do not have the built-in memory controller that is required for dual-channel mode.

Note that this has changed with the arrival of Intel's Core i7 Socket 1366 processors that have a built-in memory controller that supports dual-channel and triple-channel modes. Triple-channel mode operates using three matching memory modules. The RAM section of this website provides information on these modes of operation.

If you have bought the correct type of memory and it is installed properly, the additional module may simply be defective. Although this is not a very likely occurrence, it does happen. If it is defective and the system won't recognise it, you can't test it with the diagnostic utilities, the links to which are provided on this page of this website, and you will have to send it back to the vendor.

You could have the memory installed incorrectly, so remove it and reseat it, checking very carefully that you have it seated correctly. The notches in a memory module and socket are supposed to prevent incorrect installation, but they don't make it impossible. I have seen PCs with one or more modules installed backwards, or with one end not completely seated.

Click here! to go to the page on this site that deals with installing memory.


If you suspect you have faulty RAM memory, try using one of these free RAM diagnostic utilities

The following free utilities can test your system's RAM memory, which must be operating 100% all of the time or serious data corruption and/or system failures (that can be very difficult to track down) will occur. Note that they take a long time to go through their various tests.

Microsoft Windows Memory Diagnostic tool - with full instructions on how to use it. - http://oca.microsoft.com/en/windiag.asp

Memtest86 - latest version - http://www.memtest.org/ and http://www.memtest86.com/.

Benchmark tests

If you want to run benchmark tests on the processor, RAM, video/graphics card and hard disk drive, download PCMark04 from http://www.futuremark.com/.


How to identify the size of RAM memory modules

Question

I have purchased a large collection of RAM modules - SIMM and DIMM modules - that I want to resell, but I have no idea of how to identify the memory type and capacity in megabytes (MB) or gigabytes (GB) of the individual modules that is not provided on many of them, so I want to know if there is any way to determine the type and size of a module other than by installing it on a motherboard in a computer that supports that type of RAM.

Answer

There will no doubt not be much of a market for SIMM memory modules because they are no longer being manufactured. All recent desktop PCs use DIMM memory modules, and laptop computers use SODIMM modules.

It is possible to identify the chips by part number. You have to identify the size of each the chips on a module, and then multiply the size by the number of chips on the module to determine its memory capacity.

Different RAM manufacturers have developed their own methods of identification, so it is has become difficult to identify the chips without looking up the exact part number on a website that provides the information.

Luckily, the Internet has made doing this fairly easy. You can discover this for yourself by entering the part number as the search query into the search engine of your choice

Unless they have been remarked by unscrupulous dealers that are selling substandard modules not passed for use in a computer as computer-quality, all of the chips on a particular module will have the manufacturer's name (or logo), and a part number printed on them.

For example, a 30-pin SIMM module with nine chips on the module, could have the part number - KM41C4000AJ-8. Drop the AJ-8 (the first letter is usually the quality - A, B, C, etc., with A being the best grade), then enter KM41C4000 into the web search engine of your choice. You should be provided with links to many sites that provide information about part numbers.

The KM indicates parts made by Samsung. The 41 indicates that it is a 1Mbit x 4 memory chip. This means that the chip holds 4Mbits. Eight of the nine chips hold memory, so this is a 8 x 4Mbit, or 32Mbit module. There are eight bits to a byte, therefore this is an 4MB module. The ninth chip is there to add parity. This was used as a means of checking for memory errors that is no longer used.

For a 168-pin DIMM module that has eight chips (no parity chip), and the part number - TMS626812DGE-12A - you would use TMS626812 to search for information on it.

Each chip is a 2Mbit x 8 (16Mbit) SDRAM chip. There are eight chips, so this is a 16MB SDRAM module, which is slow compared to the fastest speed that SDRAM modules reached. The 12 in the part number indicates that the module has a maximum frequency (speed) of 66MHz. SDRAM modules, now superseded by DDR, DDR2 and DDR3 SDRAM, reached a maximum speed of 133MHz.

If you had a DDR module with the part number CT3264Z335, you know immediately from the CT that it is a module manufactured by Crucial Technology. The first link that comes up by entering CT3264Z335 in a web search should take you to Crucial's website. The page I found provided this information:

256MB, 184-pin DIMM, DDR PC2700 memory module
CT3264Z335
Module Size: 256MB
Package: 184-pin DIMM
Feature: DDR PC2700
Specs: DDR PC2700 • CL=2.5 • Unbuffered • NON-ECC • DDR333 • 2.5V • 32Meg x 64


I am confused by the types of DDR RAM memory. Which DDR RAM memory should I buy?

Problem

I am well and truly confused by the different types of DDR RAM and the AMD processors that can use them. I want to purchase an ECS K76SA motherboard, and 256MB of PC2100 or PC2700 DDR RAM. I want to run an AMD Duron 1.3GHz processor on the motherboard's front side bus (FSB), which has to be set at 100MHz with this processor installed. I know that PC2100 (aka DDR266 that runs at 266MHz) and PC2700 DDR RAM (aka DDR333 that runs at 333MHz) both run faster than double the 100MHz FSB, so I want to know if either of these types of DDR RAM will be able to run at the slower maximum bus speed used by the processor.

Answer

Read DDR SDRAM - http://en.wikipedia.org/wiki/DDR_SDRAM - for some quick information on DDR, DDR2 and DDR3 RAM memory.

Read Front Side Bus (FSB) - http://en.wikipedia.org/wiki/Front-side_bus for some quick information on it.

The processor and the DDR RAM in this case are both actually using the 100MHz FSB speed being used by the motherboard. It is only the double-data-rate (DDR) technology used by the memory itself and the motherboard's memory controller that give DDR RAM an effective running speed that is faster than the motherboard's FSB speed.

Even though the processor has a maximum internal speed (frequency) of 1.3GHz (1300MHz), the actual data transfer rate between the processor and the RAM is limited to the speed (frequency) of the motherboard's FSB, which in this case is only 100MHz.

Therefore, to run on a 100MHz FSB, which the Duron 1.3GHz processor is designed to run on, you only need to install PC1600 (DDR200) RAM, not any of the faster types shown in the table below.

Names Base FSB Speed DDR RAM Speed
PC-1600 or DDR-200 100MHz 200MHz
PC-2100 or DDR-266 133MHz 266MHz
PC-2400 or DDR-300 150MHz 300MHz
PC-2700 or DDR-333 166MHz 333MHz
PC-3200 or DDR-400 200MHz 400MHz

If you were running an Athlon XP 3200+ processor that is designed to be used on a motherboard with an FSB of 200MHz, you would use PC3200 (DDR400) RAM.

But, if you were to purchase any of the faster types shown in the table above, they would run on the system, but only at the effective DDR speed of 200MHz, which is always determined by the speed of the motherboard's FSB.

In other words, the memory controller on the north bridge chip on AMD Athlon/Duron motherboards allows the RAM bus to run at a different effective speed from the motherboard's FSB.

The base FSB on the ECS motherboard under consideration (running a Duron processor), is 100MHz, because that is the FSB used by that processor. But, by transferring data on both the rise and the fall of a single clock cycle (instead of just the rise of a clock cycle used by SDRAM), the DDR RAM is able to operate at the double-data rate, which is effectively but not actually at a speed of 200MHz (twice the FSB speed).

Later Athlon XP and Athlon 64 processors use a 133MHz, 166MHz, and 200MHz FSB.

That particular ECS motherboard supports the Athlon processors that run on an FSB of 133MHz. Therefore, the fastest memory it supports is PC2100 (DDR266) RAM. PC2400, PC2700, or PC3200 DDR RAM would work, but only at the speed of PC2100 DDR RAM.

That DDR-memory table above shows the range of FSB speeds used by the Athlon range of processors from the Athlon Thunderbird (100MHZ FSB) up to the Athlon 64 FX-51 (200MHz FSB).

The standard FSB speeds (really frequencies) of the motherboards using DDR memory are 66, 100, 133, 166, and 200MHz. Many motherboards allow a range of irregular FSB speeds to be set for overclocking purposes. For instance, on a standard 100MHz motherboard, FSB settings of 112 and 124MHz might be possible. Increasing the FSB speed is the most effective method of overclocking the processor and the RAM. The older the processor being used, the lower the range of FSB settings that the motherboard supports.

When you see systems that falsely boast of FSB speeds of 333, 400, 533, and 800MHz, this is referring to the effective speed of the DDR RAM in the single-channel or dual-channel modes of operation, not the system motherboard's maximum FSB speed.

Below are the tables for DDR2 and DDR3 memory, which runs on motherboards that support later processors than the processors that run DDR memory. The effective speed of DDR3 memory is four times the FSB speed, not twice the FSB speed applicable to DDR and DDR2 memory.

DDR Type
PC Name

Motherboard FSB

Double Data Rate (DDR) I/O Bus clock

Single-Channel Mode DDR Bandwidth
Dual-Channel Mode DDR Bandwidth
DDR2-400
PC2-3200
100MHz
200MHz
3,200 MB/s
6,400 MB/s
DDR2-533
PC2-4300
133MHz
266MHz
4,266 MB/s
8,533 MB/s
DDR2-667
PC2-5300
166MHz
333MHz
5,333 MB/s
10,666 MB/s
DDR2-800
PC2-6400
200MHz
400MHz
6,400 MB/s
12,800 MB/s
DDR2-1066
PC2-8500
266MHz
533MHz
6,400 MB/s
12,800 MB/s

DDR3 Type
PC Name
Motherboard FSB

Double Data Rate (DDR) I/O Bus clock

Effective data transfer speed
Bandwidth transfer rate
DDR3-800
PC3-6400
100MHz
400MHz
800MHz
6,400MB/s
DDR3-1066
PC3-8500
133MHz
533MHz
1066MHz
8,530MB/s
DDR3-1333
PC3-10667
166MHz
667MHz
1333MHz
10,660MB/s
DDR3-1600
PC3-12800
200MHz
800MHz
1600MHz
12,800MB/s
DDR3-1866
PC3-14900
233MHz
933MHz
1866MHz
14,930MB/s
DDR3-2000
PC3-16000
250MHz
1000MHz
2000MHz
16,000MB/s

Visit the RAM section of this site for more information on the dual-channel mode of operation of standard DDR RAM.


Some Crucial RAM memory questions

Does it matter which slots I plug my new module in?

In general, you will get the best performance if you put the largest module (in megabytes) in the lowest-numbered slot. For example, if your computer comes with 32MB of removable memory and you want to add 128MB, it would be best to put the 128MB module into slot 0 and the 32MB module into slot 1.

Why Does the Price of Memory Fluctuate?

Supply and demand. Occasional changes in market demands will alter inventories and, therefore, raise or lower prices.

Can you mix and match ECC and non-parity modules?

No. When adding new memory, you need to match what is already in your system. You can determine if your system has parity by simply counting the number of black memory chips on each module. Parity and ECC memory modules have a chip count divisible by three or five. Any chip count not divisible by three or five indicates a non-parity memory module.

Are DDR, DDR2 and DDR3 memory modules compatible?

No. There are a few motherboards that can run two types of memory, say DDR and DDR2 or DDR2 and DDR3, but only because they have the electronics (the specific DIMM slots) to do so, and you can only use one type at a time, you cannot install two different types of DDR memory at the same time. Most motherboards only support one type of DDR memory. The PC's motherboard manual, which can be downloaded in the PDF format from its manufacturer's website provides detailed information on the types and module capacities and the modes of memory that can be installed.

Can DDR and its forerunner, SDRAM, be used in the same system at the same time?

No. Even though there are systems that support both technologies, you can't have DDR and SDRAM in the same system at the same time. You'll have to choose one or the other.

What are MultiMediaCards?

About the size of a postage stamp, a MultiMediaCard, or MMC, is a small, removable storage device used in a variety of electronic devices, including digital cameras, handheld computers, and digital music players. MultiMediaCards are designed with flash technology, a non-volatile storage solution that does not lose its information once power is removed from the card. MultiMediaCards contain no moving parts and are extremely rugged, providing users with much greater protection of their data than conventional magnetic disk drives.

Crucial FAQ Center

For answers to your memory questions, visit the Crucial FAQ Center at: http://www.crucial.com/kb/.


Reported RAM memory does not match installed memory - Windows 95/98

"When you view the Performance tab in System properties, the amount of memory reported may differ from the actual amount of memory installed in the computer. This behavior can occur for any of the following reasons: Himem.sys is not using all the memory on an EISA computer. A driver or program loading from the Config.sys or Autoexec.bat file is claiming a portion of random access memory (RAM). A virtual device driver loading from the System.ini file is claiming a portion of RAM. A protected-mode driver is causing the memory mismatch. The registry is damaged. A CMOS setting is disabling some of the RAM. You have the 'maxphyspage=' setting in your System.ini file set to restrict Windows from using some of the installed memory. Ramdrive.sys is being loaded in the Config.sys file. You are using a video adapter that is integrated into the motherboard."

Click the following link to read the relevant Knowledge Base article on this problem. - http://support.microsoft.com/?kbid=146912

Applies to: Microsoft Windows 95 - Microsoft Windows 98 Standard Edition


Installing additional RAM memory on a motherboard in a Windows 98 system causes problems

Problem

My computer runs Windows 98 SE, an AMD Athlon XP 2100+ processor on a MSI KT3 Ultra2 motherboard, with 256MB of PC 2700 (aka DDR333) DDR RAM. I have bought a 256MB module of PC 2700 DDR RAM from Crucial, which comes with a guarantee that it will be compatible with this particular motherboard. However, malfunctions start occurring as soon as I installed it and booted the system. Norton Antivirus and other programs refuse to load, and the system has to be rebooted. This happens even when the new memory module is installed on its own.

Possible solutions

For a start, you aren't going to see much improvement in system performance by using in excess of 256MB of RAM on a system running Windows 98. This version of Windows was created when a large amount of RAM was rare and expensive. It was designed to run on 64MB and so double that - 128MB - is ample for most uses.

Nevertheless, Windows 98 should be able to cope with 512MB without any problems. Beyond 512MB, at around 768MB, the limitations of the Windows 98 and Windows Me memory management system are exceeded, and you will have to limit the maximum file caching via the system.ini file. To open it, enter sysedit in the Start => Run box. Look for the section of the file called [VCache]. If it isn't there, add it anywhere (on its own, not between the commands of another section) under the [386Enh] section as follows:

[VCache]

maxfilecache=522240

If that section is there, edit the existing command, and click File => Save.

Lower values than 522240 can be used. Indeed, dedicated gamers suggest setting it much lower. Read this interesting article on the subject: WINDOWS 98 & ME MEMORY MANAGEMENT - http://aumha.org/a/memmgmt.htm.

For your information, Microsoft has released a free Windows Memory Diagnostic tool, which can be downloaded from http://oca.microsoft.com/en/windiag.asp. A guide on how to use it is provided.

However, since the new module doesn't work properly on its own, Windows is unlikely to be the cause of the problem in this particular case.

That said, unfortunately, there are many other possible causes for this sort of problem, so I will start with the most probable cause.

You didn't provide its maximum power output, but I think that the power supply unit (PSU) is probably not able to handle the extra power required by the additional RAM module. So, if you have a 250W or 300W unit, buying and installing an AMD-approved 350W or 400W PSU for that processor could sort the problem out.

Note that you can't burn out the motherboard or any of the other devices by installing a PSU that is too powerful, because the components draw as much power as they need; the power is not pumped into them at the PSU's maximum power output. However, you should never switch a computer on if the motherboard has no devices installed on it or connected to it, because the PSU requires a load and will burn the PSU itself out and maybe also the motherboard if it hasn't got one to supply.

The faster the RAM, the larger the capacity of the the modules, the more power it needs to draw - and the modules from different memory chip manufacturers have different power requirements.

I have seen many cheap power supplies, which, although labelled as 350W and 400W, can't supply anything near either of those maximums as a stable power output, and have even produced voltage fluctuations when drawing a level of power that is well below the maximum stated power output. Some cheap power supplies can provide the specified power on the crucial +12V and +5V circuits, but impose a power limit on the total output of the two circuits that can be inadequate to meet a system's power requirements. That is why you should only use the power supplies made by brand-name manufacturer's such as Enermax, Antec, Tagan, and Sparkle.

Apart from an inadequate PSU, the other possible causes of this kind of problem are:

1. - RAM of poor quality (not applicable in this case, because Crucial's is some of the best RAM available)

2. - RAM that is incompatible with the motherboard (unlikely in this case because the RAM was supplied by Crucial having used its Memory Selector)

3. - An incompatibility between the existing and the new RAM modules - applicable if the modules are of different sizes or made by different manufacturers (not applicable in this case, because the new module causes the same problems on its own)

4. - Motherboard issues stemming from its having to use very large memory modules (also not applicable in this case)

There is a great deal of RAM of poor quality on the market, so buying it from a high-quality manufacturer, such as Crucial, is the best guarantee of receiving RAM that will work the first time it is installed. Crucial's technical staff have compiled an extensive database of the idiosyncrasies of particular makes and models of motherboard, which it uses to make sure that the RAM it provides for a particular brand-name computer or motherboard will function properly.

Visit crucial.com to use the UK and US Crucial Memory Advisor that is provided from there for several countries.

If you were installing a faster processor or faster RAM, there could be motherboard BIOS issues relating to the faster hardware that could be rectified by installing a BIOS flash upgrade. If a faster processor was installed (not applicable in this case), you should make sure that the processor's core voltage stated in the BIOS matches the voltage stated on the face of the processor.

Therefore, it would appear that either the new module is faulty, or the PSU is inadequate.

If the module can be installed and the system successfully booted from a floppy disk, you could test the RAM by using MemTest, a free the DOS-base diagnostic utility that runs from a floppy disk.

If doing that isn't possible, and upgrading the PSU doesn't work, you'll have to return the module to Crucial.


Why does a double-sided DDR RAM memory module work in one DIMM slot but not in the other two DIMM slots on my motherboard?

Problem

My Chaintech ZNF3-250 motherboard runs an AMD Athlon 64 3200+ processor and 1GB of Kingston DDR 400 Value RAM in the form of two double-sided modules. If it boots that far, all of the RAM is checked and registers at start-up, but it's very unstable and makes the system freeze most of the time during the boot process. I read the motherboard's manual and discovered that only the first DIMM slot is compatible with a double-sided DDR RAM module. This is true because the computer runs properly if I use only one of the modules. If the other two DIMM slots are incompatible with the RAM I have, why is all of the RAM registered at start-up, and is there anything I can do in the way of, say, BIOS settings that will enable me to use the other module?

Answer

Double-sided DDR RAM modules have 16 memory chips (eight on each side of the module), and single-sided modules have only eight memory chips on one side of the module, or are engineered to have four memory chips on each side of the module, but run as if all of the chips are on the same side of the module.

That particular Chaintech motherboard has an nVidia nForce3-250 chipset and supports the new generation of AMD Socket 754 Athlon 64 processors. The specifications for any motherboard are provided in its user manual, which should be available as a download from its manufacturer's site. However, that option is not available to you, because Chaintech the motherboard maker is now called Walton Chaintech and it only manufactures memory products and no longer even supports the motherboards it manufactured.

I like the way this page enables easy access to BIOS updates, a Utility, the user manual, motherboard drivers, and a RAM memory compatibility list. It's a Flash site the pages of which will be slow to load on a dial-up connection.

According to the user manual, the first DIMM slot can support 1GB of DDR RAM in the form of a single- or double-sided module, but the second and third DIMM slots can only accept single-sided modules up to a total of 1GB between them.

It's difficult to have such large capacities of RAM running at high speeds without timing problems causing instability. This is especially the case with double-sided modules that have the memory chips on both sides of the module. The motherboards for both Intel (Pentium 4) and AMD (Athlon XP and Athlon 64) processors usually suffer from stability problems when running double-sided modules.

If you read AMD's specifications for the Athlon 64 processor, you'll discover the admission that it can't handle the timing issues involved in running more than one double-sided module at the full DDR 400 speed. According to the same specifications, it states that systems with two or more double-sided modules can only be operated at the speed of DDR 333 modules.

As usual, AMD is being rather conservative with its specifications, probably in order to avoid as many problems as possible. Some Athlon 64 motherboards will run as much good-quality double-sided memory (i.e., made by Crucial) as the board can be fitted with without any problems, and others support a maximum capacity of particular brands of DDR 400 RAM that should run without problems.

An nVidia nForce chipset of the kind found on that Chaintech motherboard has two independent 64-bit DDR RAM memory channels. The first DIMM slot uses one entire channel by itself, and the bandwidth of the other channel is shared by the two other DIMM slots. That is why Chaintech recommended that a double-sided module should only be fitted in the first DIMM slot, with single-sided modules fitted in the other two slots.

The capacity of a module is read from a small chip on it called the Serial Presence Detect (SPD), and that is why the full capacity of the two double-sided modules was registered even though both of them wouldn't allow the system to run.

Since the problem involves timing issues, a BIOS update might have be able to rectify the situation, but as was said earlier, Chaintech no longer makes motherboards, just memory products, and no longer supports the motherboards it made.

Indeed, both of those modules might work if you just tweak the BIOS settings for the memory timings slightly. For example, increasing the Cas Latency setting, usually under the Chipset Features Setup in the BIOS, from 2 or 2.5 to 3 might do the trick. Moreover, it's known that some motherboards with this chipset only have the problem with one DIMM slot, so inserting the second module in the third slot might work.

Single-sided modules have eight memory chips, which can be 256Mbit or 512Mbit chips. If 256Mbit chips are used the module can only have a capacity of 256MB. 512Mbit chips, which are much more expensive, have to be used for a single-sided 512MB module. This is why a 1GB single-sided module is considerably more expensive than two 512MB single-sided modules - the very expensive 1024Mbit memory chips have to be used. Double-sided modules use the cheaper 256Mbit chips for 512MB modules, because they have 16 memory chips per module. Therefore, a 1GB double-sided module has to use the 512Mbit chips.

Using single-sided modules is the only guaranteed way to have large amounts of RAM installed and running with stability at its full speed.


My Windows XP computer doesn't recognise 1GB of RAM memory when 4GBs are installed

Problem

I have a new PC with an AMD Athlon 64 x2 4200+ (dual-core) processor, running Windows XP Pro SP2. I had 2GB of RAM installed, then installed another 2GB, but the system can only recognise 3GB. A search of the MS Knowledge Base has left me no wiser. If I can't get the 1GB to work, I'll have to exchange the two 1GB DIMMS for two 512MB DIMMS. What's the point of a motherboard that can take four 1GB DIMM modules if Windows XP Pro doesn't recognise that much?

Answer

Windows XP can run in as little as 64MB of RAM. Microsoft recommends 128MB as a minimum, but 256MB is the real minimum, with 512MB just what the doctor ordered. Windows XP can handle (address) up to 4GB of RAM.

From reading your question I take it that you have a 1GB DDR DIMM module in each of the four DIMM slots on the computer's motherboard. Are they all made by the same manufacturer and of the same type? (DDR333, DDR400, etc.)

Click here! to go to information about DDR RAM on this site. At the time of writing (August 2004), AMD had yet to introduce support for DDR2 RAM in its Athlon 64 processors, so you must be using DDR modules.

The motherboard's or the brand-name PC's user manual should tell you the amounts and types of RAM that can be installed in each of the DIMM slots, so read to find out if your installation of RAM is supported.

If the configuration of the RAM you have installed is supported, you should know that some motherboards can be finicky about which slots can accept which types of RAM, and/or be finicky about mixing different types of DDR RAM. You should therefore make sure that all of the DDR RAM is of the same type. If the RAM is made by different manufacturers, install only RAM made by the same manufacturer. Crucial is the best RAM from a compatibility point of view. You can sell any RAM made by another manufacturer on an auction site such as eBay.

I have come across several cases in which one make of RAM works in one make and model of motherboard but not in another motherboard, and some makes of RAM simply is not compatible with a particular motherboard or make of motherboard. That is why motherboard manufacturer's websites usually provide a list of compatible makes of RAM.

A common remedy for some RAM issues is simply to juggle the RAM modules around. In other words, try different modules in different DIMM slots. With identical RAM modules, this shouldn't make any difference, but, for some reason, sometimes it does. In any case, but trying different modules in different slots, you can often determine which DIMM module or DIMM slot is faulty.

In acting on the above information is of no help, the problem is probably a hardware or BIOS issue rather than an issue with Windows XP.

You should check the brand-name PC's or the motherboard manufacturer's website for any pertinent information. For example, a BIOS update might fix a bug in the amount of RAM that can be installed. You should also experiment with the the BIOS settings that apply to the RAM. The PC's or the motherboard's user manual has a section on the BIOS settings. You can try settings higher timings to see if it makes a difference. As a last resort, you can try reflashing the BIOS with the latest update from the PC's or the motherboard manufacturer's website. Once the BIOS can recognise all of the RAM, Windows XP will probably do likewise.

However, the problem may be a faulty motherboard, which makes it a warranty issue.


Which type of RAM memory do I have to install to upgrade my PC?

Question

Unfortunately, I have a Time PC. The company that owned Time Computers and Tiny Computers went out of business at the end of July 2005. I therefore can't buy the upgrade from the PC's manufacturer, so can you tell me how to get the correct RAM?

Answer

Your Time computer should have come with a user manual that identifies the model. All you have to do to obtain the correct RAM is to make use of the UK Crucial Memory Selector that is provided from crucial.com/uk. Crucial guarantees that the RAM will work if you buy it for a particular make and model of PC or PC motherboard or your money is refunded. Standard postal delivery is free.

If you want to identify the type of RAM that is installed in the PC, use the free CPU-Z utility. Click on the utility's Memory and SPD tabs to see the information on the RAM. If you click on the About tab, you'll see an HTML Report button. Clicking on it creates a report in thw form of a web page that you can save to your desktop or a folder, such as My Documents.

If you can't identify the model because you don't have a user manual and the model isn't shown anywhere on the PC's case, or you would prefer to buy your memory from a local dealer, print the report and show it to a member of the store's staff. The information that is relevant is found at the bottom of the Memory section of the report, where the amount of memory that is installed in each of the DIMM memory slots is provided. E.g., Module 0: - Micron Technology DDR-SDRAM PC2700 - 256 MBytes. Module 1: Micron Technology DDR-SDRAM PC2700 - 256 MBytes. The memory in the first DIMM slot or bank is called Module 0.

If the computer uses SDRAM (the forerunner of DDR RAM), the types of memory you need are either PC66 (runs at 66MHz), PC100 (100MHz), or PC133 (133Mhz). PC133 modules can function in most systems that use PC66 or PC100 memory. In general, with both SDRAM and DDR RAM, the faster modules can usually run from motherboards that only support the slower modules, but you shouldn't use the slower modules in a system that supports the faster modules because of the detrimental affect that doing so will have on the system's performance. However, DDR RAM cannot be used in a system that uses SDRAM, and vice versa.

Your computer probably uses DDR RAM if it was purchased in 2000 or later, because SDRAM was used in computers between 1997 and 1999. Click here! to go to the information on DDR RAM on this site.


A RAM memory upgrade won't work in my laptop computer

Problem

My Dell Inspiron 5000e came with 64MB of RAM memory installed. Dell's website says that it can use a maximum of two 256MB PC100 SODIMM memory modules. I bought an 128MB module of Micron memory that uses the same chips (48LC8M16A2) as the 64MB module, but which has eight chips instead of the four chips that the 64MB module has. However, the computer won't boot with the upgrade installed, fitted with or without the original module, and using either of the two memory banks. It cycles on an off about every ten seconds. I have also tried a module of PC133 memory that someone gave me to try, but the same problem occurred. I didn't expect the PC133 module to work, because it is CL3 instead of CL2 memory. I've read that some computers are very fussy about the memory that they can use. Could that be the cause of the problem?

Answer

The Dell Inspiron 5000e is known to be fairly fussy about memory timing, but the 128MB module that you tried should have worked if it uses the same chips as the 64MB module. The new module may be faulty. Did you try the 64MB module in the second memory bank in order to find out if it is functioning? Because the second memory bank could be faulty. The computer's user manual should tell you if a memory module can't be installed in the second memory bank without a module also being installed in the first memory bank.

PC133 memory of the correct density can be used in systems that specify the use of PC100 memory, and, having a higher maximum clock speed, can even be preferable, even though it will only run at the speed of PC100 memory. There are cases in which mixing different memory modules, such as CL2 and CL3 memory, causes problems, however these are rare and are usually due to peculiarities of particular motherboards. Some older Dell and Gateway computers can only use a particular CL2 module known as 'two-clock memory'.

For computers that are known to be fussy about memory timings, Crucial is the best brand to buy. It is manufactured by Micron, which guarantees that any upgrade memory used in any particular system will be compatible if it is ordered by entering the correct system details in its Memory Advisor. You would use the Memory Advisor to look for memory for the Dell Inspiron 5000e.

You can make use of either the UK or US Memory Advisors provided at the top of this page.

At the time of writing this (November, 2007), a 128MB module was priced at £18, and a 256MB module at £34, including standard delivery. It can be returned for a refund if it won't work in your computer.


Advice on how to upgrade the RAM memory for a PC with an Asus A7A266 Socket A motherboard required

Question

I have a six-year-old desktop PC, the RAM memory of which I've already upgraded to 512MB. It runs Windows XP Professional Edition and has an Asus A7A266 Socket A motherboard. It currently has a two 256MB 184-pin DIMM modules installed. The motherboard manual says that the maximum supported memory is 2GB of DDR memory and 3GB of SDRAM. I find this very confusing. What's the maximum amount of memory I can actually use?

Answer

The Asus A7A266 is an unusual motherboard. It arrived at the time when one type of memory was being replaced by another type, so it has memory slots for both types. It has slots for both the older PC133 SDRAM and the newer DDR SDRAM memory modules. Since that motherboard was made available DDR2 and DDR3 memory has become available, both of which are incompatible with DDR memory. DDR, DDR2 and DDR3 memory will only fit in motherboard slots that are designed to use only one type. Transitional motherboards are available the can accommodate DDR/DDR2 and DDR2/DDR3 in separate slots, just like the Asus A7A266 does with SDRAM/DDR memory, but most motherboards only support one type.

There are three DIMM slots on the Asus motherboard that will take PC133 SDRAM memory, and two DIMM slots for DDR memory. However, you must use one type or the other; they cannot be mixed.

In 2001, when the motherboard came out, DDR memory was faster but was very expensive. Now it is the obsolete PC133 SDRAM memory that has become expensive, while DDR memory is cheap. Although the motherboard manual says that the motherboard supports 3GB of PC133 memory, in practice there are problems when the modules in each slot are any capacity above 256MB, making a maximum of 768MB (3 x 256MB). In any case, at current prices (June 2008), while 1GB of PC2700 DDR memory costs L33 from Crucial, a 1GB module of PC133 SDRAM memory costs three times as much. You can install 2GB using two 1 GB PC2700 DDR DIMM modules in the DDR slots. The original specification of the motherboard required the use of PC2100 DDR memory. However, since DDR memory is backwards compatible, you can use any DDR memory rated for this speed and faster (PC3200 and PC4200), but you should not use the slower PC 1600 or PC 2100 memory.

Below is an extract from a motherboard manual for a motherboard that supports both DDR and DDR2 memory. The placement of notches on the modules make it impossible to install the module in a DIMM slot that does not support a particular type of DDR memory.

Motherboard manual warning that the motherboard can only support either DDR or DDR2 memory, not both

Articles on RAM memory errors and problems in the Microsoft Knowledge Base

Click the MS Knowledge Base reference number below to go to that article
Description of the problem
Click the link =>
Windows Vista RAM memory problems
Click the link =>
Windows 7 RAM memory problems
946003
Windows Vista SP1 will report 4 GB of system memory (RAM) on systems that have 4 GB of memory installed - After you install Windows Vista Service Pack 1 (SP1), the memory (RAM) value reported by Windows Vista may increase if the following conditions are true:• The system BIOS has reserved physical memory for graphics or for other peripherals. • Your computer has more than 3 GB of system memory installed. This change occurs because Windows Vista with SP1 reports how much physical memory installed on your computer. All versions of Windows NT-based operating systems before Windows Vista Service SP1 report how much memory available to the operating system. This change in Windows Vista SP1 is a reporting change only.
929605
The system memory that is reported in the System Information dialog box in Windows Vista is less than you expect if 4 GB of RAM is installed - If a computer has 4 gigabytes (GB) of random-access memory (RAM) installed, the system memory that is reported in the System Information dialog box in Windows Vista is less than you expect. For example, the System Information dialog box may report 3,120 megabytes (MB) of system memory on a computer that has 4 GB of memory installed (4,096 MB).
330909
Hibernation Problem on Computers with 1 GB of RAM [Applies to Windows XP]
555223
RAM, Virtual Memory, Pagefile and all that stuff - Windows XP Home and Professional Editions
810093
Error Message with RAM Problems or Damaged Virtual Memory Manager - When your computer restarts after you install Windows XP Home Edition, you may receive either of the following error messages: System has recovered from a serious error DRIVER_IRQL_NOT_LESS_OR_EQUAL - This behavior may occur if either of the following conditions exist: • One or more of the random access memory (RAM) modules that are installed in your computer are faulty, or the memory modules are not compatible with the chip set on your computer mainboard. • The Page file that is used by the Virtual Memory Manager may be damaged.
326687
"Bad Image Checksum" Error When You Upgrade to Windows XP - When you upgrade your computer to Windows XP, you may receive an error message that is similar to one of the following: C0000221 (Bad Image Checksum) -or- STOP: C0000221 - Bad Image Checksum in ModuleName -or- STOP: C0000221 - Bad Image Checksum. User32.dll is possibly corrupt. The header check sum does not match the computed check sum. - This issue may occur if any of the following conditions exist: • A damaged file exists in the folder in which Windows is installed, and this file is not overwritten during Setup. For example, if you receive the error message that references the User32.dll file, the User32.dll file may be damaged. • One or more of the random access memory (RAM) modules that are installed in your computer is faulty, or the RAM configuration is incompatible.
316400
"An Unexpected Error Has Occurred (536821760)" Error Message When You Try to Install Windows XP - When you attempt to install Windows XP, the installation process may not complete successfully. Setup may stop at the beginning of the process or immediately after the first required restart, and then you receive an error message similar to the following: An unexpected error has occurred. (536821760) occurred at line 1768 in D:\xpclient\base\boot\setup\arcdisp.c - This behavior can occur because of damaged random access memory (RAM) modules or a damaged RAM slot.
315335
"STOP 0x0000008e" error message during Windows XP setup - When you install Microsoft Windows XP, you may receive a Stop Error message that is similar to one of the following while the Setup program is running: STOP 0x0000008e STOP 0x00000050 PAGE_FAULT_IN_NON_PAGED_AREA Additionally, if you troubleshoot by removing all unnecessary hardware devices that are installed on the computer, and then you run the Setup program, you may receive an error message that is similar to the following: Setup cannot copy the file Setupdd.sys. - This behavior may occur if one of the following conditions is true: • One or more of the random access memory (RAM) modules that are installed on your computer are faulty. • The RAM configuration is incompatible with Windows XP.
318263
RAM memory leaks and how to detect and isolate them [General article]
253912
"Out of Memory" Error Messages with Large Amounts of RAM Installed [Applies to Windows 95/98/Me - Windows 98 SE (Second Edition) has trouble with 512MB of RAM and more. Windows 95/98/Me systems were not designed to use large amounts or RAM. Most home users of Windows 95/98/Me are unlikely to require this much RAM in any case, so, if possible, it's advisable to install less than 512MB. The fix is detailed in this article]
304943
Computer May Reboot Continuously with More Than 1.5 GB of RAM - If your computer has more than 1.5 gigabytes (GB) of memory (RAM), the computer may reboot continuously when you try to start Windows Millennium Edition (Me) or Windows 98. Or, when you try to install Windows Me or Windows 98 with more than 1.5 GB of RAM installed, Setup may stop responding (hang) or reboot continuously. - Windows Me and Windows 98 are not designed to handle more than 1 GB of RAM. More than 1 GB can lead to potential system instability.
177864
Insufficient RAM Memory to Load System Files [Applies to Windows 98 Standard Edition / Windows 95]
826289
Computer Stops Responding During the Memory Check Phase of the Startup Process [Applies to Windows 2000 Professional Edition ]
142546
How to Use a RAM Drive to Troubleshoot RAM Memory [Applies to Windows 95/Windows 98 Standard Edition/Windows 98 Second Edition]
146192
Reported Memory Does Not Match Amount of Installed Memory - When you view the Performance tab in System properties, the amount of memory reported may differ from the actual amount of memory installed in the computer. Applies to Windows 95 and Windows 98 Standard Edition
184447
Error Message - Insufficient Memory to Initialise Windows - when 1 gigabyte (1GB) or more of random-access memory (RAM) is installed [Applies to Windows 95/98/98 SE]

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