RAM Memory Problems: Fixing Problems with DDR/DDR2/DDR3 RAM

	SEARCH THIS SITE:
	Web www.pcbuyerbeware.co.uk

Visit the RAM - Random Access Memory - What it is and how to buy the right type article on this site for more information on it.

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 take a 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 disk, you can run the diagnostic 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/

The safest way to upgrade RAM: Use the UK and US Crucial Memory Advisors

Paul Mullen, the highly-respected computer guru of the Helpfile at ComputerShopper.co.uk - "I have recently been buying my memory only from Crucial Technology. I would rather pay the extra cost than waste time trying to track down the obscure program faults that bad memory can cause."

The memory requirements of the versions of Windows Vista

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 amount recommended for Windows XP. Windows Vista Home Premium, the most popular version, and Windows Vista Ultimate require a recommended minimum of 1GB (1024MB) of memory, which is twice the amount of minimum memory recommended to run Windows XP. For more information on computer memory, read the RAM pages of this site.

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 on the subject:

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

For example, if your computer has an Asus motherboard, open the menu, scroll down to ASUS, and click GO. If, say, you have a Dell computer, scroll down to DELL, and do likewise. You will be taken to the relevant information on Crucial's website.

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 - http://www.belarc.com/. Another utility that also provides detailed information on the memory itself is CPU-Z.

RAM MEMORY PROBLEMS

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. - Faulty RAM/motherboard/power supply: My PC constantly reboots 10 to 20 minutes after being switched on

3. - Can I install 4GB of RAM memory in my computer?

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

5. - The memory requirements of Windows Vista: How much RAM memory does Windows Vista really need to run optimally?

6. - 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

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

8. - Should I install single memory modules or matched-pair modules on my motherboard that supports single-channel and dual-channel modes?

9. - My PC doesn't recognise [US: recognize] the new RAM memory I installed

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

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

12. - Which DDR/DDR2 RAM memory?

13. - Some Crucial RAM memory questions

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

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

16. - 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?

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

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

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

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

Faulty RAM/motherboard/power supply: My PC constantly reboots 10 to 20 minutes after being switched on

Problem

I have a problem with my desktop PC (Windows XP, AMD Athlon 1700+, 256MB of RAM, 80GB 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 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, 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 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 - http://www.belarc.com/. Another utility that also provides detailed information on the memory itself is CPU-Z.

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 Advisors provided at the top of this page 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.

Find out if your PC is overheating with this free utility:

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

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 bad.

Can I install 4GB of RAM memory in my 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.

Answer

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. 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 have less than 3GB of memory installed, because they don't support more than that amount of memory. The 64-bit version of Windows XP Professional supports a maximum of 8GB of memory.

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 3GB 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 on the following two pages:

Desktop CPU Comparison Guide - AMD processors - http://www.techarp.com/showarticle.aspx?artno=337&pgno=0

Desktop CPU Comparison Guide - Intel processors - http://www.techarp.com/showarticle.aspx?artno=337&pgno=4

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/windowsvista/editions/64bit.mspx

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?

Kingston Technology - Ultimate Memory Guide -

Covers Windows Vista, Windows XP, Windows 2000, Windows 98, Linux, and Macintosh OS X. - http://www.kingston.com/tools/umg/umg01b.asp

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 (800MHz) DDR2 RAM 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 (800MHz) DDR2 RAM memory. But when I use the CPU-Z utility, under the Memory tab, it reports the memory as running at only 333MHz. Why is that the case?

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. If you don't have a manual, you can use CPU-Z to identify the make/model of the motherboard and then use the Google search box at the top of this page (with its Web radio button enabled) 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 site 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. Make sure that you 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 memory requirements of Windows Vista: How much RAM memory does Windows Vista really 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 Windows XP Pro very well. It came with a free upgrade to Windows Vista Business edition, which I have applied for. 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 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/article.do?command=viewArticleBasic&articleId=9011523&intsrc=hm_list

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, and that cannot be changed.

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.

Windows Vista would run on a desktop or laptop computer with that hardware, but it won't be an enjoyable experience - especially if it is one of the higher versions 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 amount of memory of 512MB, which is the same amount recommended for Windows XP. Windows Vista Home Premium, the most popular version and Windows Vista Ultimate require 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.

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.

Microsoft's "recommended" hardware, which includes a 1GHz processor, 1GB of RAM, a video/graphics card with at least 128MB of video RAM, a Windows Vista Display Driver Model (WDDM) device driver, and 32 bits/pixel output, is a more realistic practical recommended minimum for a Windows Vista Capable computer.

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. For your information, the 64-bit versions support more than that. But does Vista really need 4GB of memory? - No. 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 higher versions of Vista optimally, 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 probaby run Windows Vista Business edition just acceptably well on 2GB less 128MB (2048 - 128 = 1920MB).

Kingston Technology - Ultimate Memory Guide -

Covers Windows Vista, Windows XP, Windows 2000, Windows 98, Linux, and Macintosh OS X. -

http://www.kingston.com/tools/umg/umg01b.asp

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 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

An LGA775 motherboard that has four DIMM 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 4GB of memory in the 32-bit versions of Windows XP and Windows Vista. Your PC's 850W power supply can easily power that much memory. Therefore, either you have a bad module or your motherboard has a bad DIMM slot/memory bank.

To find out if you have a bad 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 bad 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 bad DIMM slot. Consult your motherboard's manual to find out what the different combinations of modules are that can be installed in the slots. If you don't have a motherboard manual, download a manual in the PDF format from it's manufacturer's site. By installing different permitted single modules or combinations of modules, you should be able to determine which of the slot's is bad. You could get three modules to boot, so, if one slot is bad, 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 memory in my computer, making 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 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.

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 bad.

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 manual, you can use CPU-Z to identify the make/model of the motherboard, and then use Google to find out 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.

If I install one module of 2GB DDR2 RAM memory in my PC's GIGABYTE GA-MA78GM-S2H motherboard it 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 of RAM, 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.

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 and Vista), 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 http://www.gigabyte.com.tw/ 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 http://www.gigabyte.com.tw/ by 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 at the top of this page to buy 4GB of Crucial memory for that make/model of motherboard. 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 single memory modules or matched-pair modules on my motherboard that supports single-channel and dual-channel modes?

Question

I have an Asus A8V motherboard that is running an AMD Athlon 64 x2 dual-core processor. It has four DIMM memory slots and supports the installation of single memory modules that run in single-channel mode, or a matched pair of modules that run in dual-channel mode. I need to know which is the best option: 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. With your motherboard, the modules are installed in the first and third DIMM slots (slots 1 and 3). Consult the motherboard's manual for an illustrated installation guide. 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.

A matched pair of modules are sold together in a single package, 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. Single modules 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 that are identical down to the finest detail.

Note well that the PC should have a power supply unit 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 of that motherboard (slots 2 and 4), but fail to run them in the dual-channel slots (1 and 3) 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. 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. However if you started with a 1GB module installed in a single-channel memory slot, you can upgrade to using 4GB by installing a 1GB module in each of the four slots, because when all of the slots are used they can only work in single-channel mode.

My PC doesn't recognise [US: recognize] the new RAM memory I installed

Problem

I have a new HP Media Center PC that runs an Intel pentium D 2.8GHz dual-core processor with 1GB of RAM. 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 latest DDR2 RAM, because that is what Intel's Pentium D processor's use. However, you might have purchased a standard DDR 512MB module, or even a module of the even earlier SDRAM. Using the wrong type of memory could make the system fail to recognise it. In other cases, installing a module of the wrong type of memory to existing memory could make a PC fail to boot. You didn't provide the specifications of the additional module, you only say that it is a 512MB module.

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's website 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 hat 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 at the top of this page. 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. The user manual that came with the PC should tell you which of the DIMM slots on the PC's motherboard can be used to install identical modules (the same type and size) so that they work in dual-channel mode. If you don't have a user manual, you should be able to download a copy from HP's site, or you could identify the make and model of the PC's motherboard and download its user manual from its manufacturer's site.

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 - http://www.belarc.com/. Another utility that also provides detailed information on the memory itself is CPU-Z.

You say that you added a 512MB module to the existing 1GB, but you didn't say what the 1GB is made up of. Is it installed as two 512MB modules, or is it installed as a single 1GB module? That is important, because if two 512MB modules are installed in DIMM memory slots that allow them to work in dual-channel mode and you then install just one module in one of the other slots, it might not be recognised because the motherboard doesn't allow a single module to be installed in the slot you installed it in. To work in dual-channel mode, you have to install two identical memory modules in two DIMM slots that support that mode of operation.

If you have a 1GB module installed in a DIMM slot that supports single-channel mode it will work, but it might not be recognised if you were to install it in a DIMM slot meant for one of two modules working in dual-channel mode.

The PC's or the motherboard's manual should tell you which DIMM slots allow which sizes of modules (256MB, 512MB, 1GB, etc.), and which of them support dual-channel mode and which of then can be used with single modules working in single-channel mode.

Click here! to go to more detailed information on DDR and DDR 2 memory on this site.

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 on this site, 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, 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

You have purchased a large collection of RAM modules - SIMMs and DIMMs - that you want to resell, but you have no idea of how to identify the memory capacity in megabytes (MB) of the individual modules, and you want to know if there is any way to determine the size of a module other than by installing it on a motherboard in a computer that supports that type of RAM.

Answer

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 using the Google search box at the top of this page.

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.), then enter KM41C4000 in the Google search box at the top of this page. 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 part. 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 and Rambus RAM, reached a maximum speed of 133MHz.

Which DDR/DDR2 RAM memory?

The problem

You are well and truly confused by the different types of DDR RAM and the AMD processors that can use them. You want to purchase an ECS K76SA motherboard, and 256MB of PC2100 or PC2700 DDR RAM. You 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. You 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 you 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

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.

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 table 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 currently still in regular use 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.

See the RAM page 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.

Can DDR and 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. For the technical details on this subject, visit More RAM, More Speed, More Power -

http://www.overclockers.com/articles696.

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.

To use the UK and US Crucial Memory Selectors that are provided there, see the RAM page on this site.

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. You can use the Google search box at the top of this page to locate the nearest Chaintech site.

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 recommends 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, perhaps a BIOS update might be able to rectify the situation. To find out if an update is available, visit Chaintech's site at http://www.chaintech.com.tw/ and search for ZNF3-250.

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 on the first of the pages that provide information on RAM on this site. Just make a note of the model and then click here! to visit that page. Find the UK Crucial Memory Selector, click on its drop-down menu, scroll down to Time, and click on the GO! button. You will be taken to a page on the Crucial UK site. Open the drop-down menu on that page and scroll down to the model you have. You will then be shown a page that lists the types of RAM and the sizes of the modules that tour PC can run. 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 from http://www.cpuid.com/. 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.

PC Buyer Beware! Copyright © Eric Legge 2004-2008. All rights reserved.