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Motherboards (Mainboards), PC Cases, and Power Supply Units (PSUs) - Page 2

The Power Supply Unit (PSU) used in desktop PCs/computers; making a good choice of motherboard, etc.

Last updated on 12 March 2010

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CONTENTS

Page 1 - The motherboard (mainboard) and PC case used in desktop computers

Page 3 - Sundry useful motherboard information

The Power Supply Unit (PSU) Used in Desktop Computers

The image above shows two PC power supply units.

NEVER OPEN A POWER SUPPLY UNIT. ITS CAPACITORS CAN CARRY A LETHAL CHARGE LONG AFTER IT HAS BEEN SWITCHED OFF!

NOTE WELL - BEFORE TURNING A POWER SUPPLY ON, ENSURE THAT THE VOLTAGE SELECTION SWITCH ON THE PSU IS SET CORRECTLY (230V in the UK -115V in the USA).

Failure to ensure this switch is set to the correct voltage will probably destroy your PSU. - And do not use the power supply unit unless it has a load attached to the motherboard, such as the video card and hard disk drive. Turning the power on with only the motherboard attached to it, could also destroy the power supply unit, which must have a load to function without burning out.

The job of the power supply unit (PSU) is to deliver a stable voltage to the PC's components. If it does not do that, the PC will crash (stop working) and the components can be fatally damaged.

The power supply unit is one of the most overlooked components in a PC. I suppose the reason is that most people simply believe that if a power supply unit has the physical capacity to be connected to as many other components via the motherboard then it must be able to deliver the quality of power that they require. Unfortunately, that is often not the case, because the power supply in a desktop computer, or the power supply that comes with a PC case, can be underpowered or of low quality. If that is the case and you install a high-end graphics card or a dual-core or quad-core processor, the system could become unstable or might even fail to boot.

Note that most power supplies should fit into a standard ATX case, but some of them, such as the Zalman ZM500-HP, Hiper Type M 670W, and Tagan Dual-Engine 700W, have more depth than is usual, so make sure that you can fit a power supply in your PC case before you buy it.

In the UK, a power supply uses the 230V AC mains supply and tranforms it into power at the correct voltages for the computer's components.

Different components require different voltages, so a power supply is really several power supplies in one unit. Each supply is called a rail. All power supplies have three main rails - 3.3V, 5V, and 12V - two secondary standby rails - 12V and 5V. A power supply's maximum wattage (e.g., 700W) is the total power it can supply across all of its rails. Some power supplies can have up to four 12V rails. These are used to power PCs running powerful components so that they can each have their own rail. The 12V rail (or rails) is/are of particular importance because it/they powers/power the PC's processor and graphics card.

However, test of quality power supplies that use both a single 12v rail and more than one are found to be stable at all loads.

Power supply rail - http://en.wikipedia.org/wiki/Power_supply_rail

Each make/model of power supply has its own rating for the amount of power in watts (W) that each rail can deliver. However, the total power rating of a power supply cannot be determined by adding up the rating for each rail, because each rail will not have to be delivering full power all the time. The rating for each rail is just the maximum power that it can deliver if power is available from the total that the unit can generate.

A PC that has a dual-core processor and a mid-range graphics card, such as an nVidia GeForce 8800 GT draws about 250W, so you won't be able to use a 250W power supply because the 12V rail won't be able to deliver the full 250W. A 250W unit is designed to provide power to all of the PC's components, not just the processor and the graphics card. Therefore, it is a good idea to have a power supply that has a total power rating that exceeds the PC's power demands. The same PC with a quad-core processor would require about 320W, so it would be advisable to use a 450 - 500W power supply.

The latest high-end graphics cards can draw up to 300W on their own, which means that you would need a power supply rated as 600 to 650W. However, if you have two graphics cards installed using SLI or CrossFire technology, which the motherboard must support, you may require a 700 to 800W power supply.

You can also now install four graphics cards, which will demand even more power.

"Arm yourself with up to four ATI Radeon HD graphics cards to move faster, aim quicker, and see more clearly than all who stand between you and victory. With an ATI CrossFireX gaming rig, you can breakthrough traditional graphics limitations to achieve higher performance and The Ultimate Visual Experience™."

The current ATX12V 2.0 standard for power supply units has replaced the previous ATX 1.3 standard.

The old ATX 1.3 standard has a 20-pin power connector that connects the power suppply to the motherboard. The new ATX12V 2.0 standard uses a 24-pin power connector.

An adapter is required to be able to use the new 24-pin plug of a ATX12V 2.0 power supply in motherboards that have theolder ATX 1.3 20-pin connector. Most power supply manufacturers include one with their new ATX12V 2.0 power supplies, because 20-pin connectors are still being used on many motherboards. A 20-pin power-supply cable also fits into the adapter, making it possible to use an old-style power supply unit with a motherboard that has the new 24-pin connector.

An ATX12V 2.0 power supply has several four-pin Molex and SATA connectors/plugs. Molex plugs are connected to IDE ATA CD/DVD optical drives and IDE ATA hard disk drives, and some AGP graphics cards. SATA connectors/plugs connect to SATA hard disk drives and optical SATA CD/DVD drives. Molex-to-SATA adapters that make an Molex plug into an SATA plug are readily available, but SATA-to-Molex adapters are not. You should make sure that any power supply that you buy has enough Molex and SATA cables to connect to the drives that your PC has.

Powerful high-end PCI Express graphics cards connect to a six-pin power connector from the power supply, so if you buy such a card your PC's power supply must have one. The most powerful PCI Express graphics cards require two such connectors, which are also required for dual-card setups.

Note that the very latest ATI graphics cards use a six-pin and an eight-pin PCI Express connector. The Enermax Infiniti 650W power supply provides the correct eight-pin plug.

A dual-core processor can draw up to 130W on its own, and nVidia and ATI recommend the output of the power supply that can run two or four of their high-end graphics cards in SLI mode and CrossFire/CrossFireX mode respectively.

If you plan on using two or four graphics cards that use either nVidia's SLI technology or ATI's CrossFire/CrossFireX technology, make sure that your PC has a power supply that explicitly states in its specifications that it supports the particular technology that you want to install.

Both nVidia and AMD (ATI) have certification programs for power supplies that are guaranteed to work with two or four graphics cards using SLI or CrossFire/CrossFireX.

A full list of power supplies and the graphics cards that they support can be found at at http://www.slizone.com/ (for nVidia cards) and http://game.amd.com/us-en/crossfirex_about.aspx.

Recommended makes of power supply? - The image above shows power supplies made by tardshe major manufacturers Enermax (top) and Antec. Both companies make cases with power supplies, and separate power supplies. Akasa, Cooler Master, Zalman, Seasonic, and Tagan are reputable major manufacturers of power supplies.

There are many smaller, less well known manufacturers of quality power supplies, such as Jeantech, that makes cases and PSUs. The best-known supplier of Jeantech products in the UK is PC World.

Note that the power supply must be able to run the hardware components that it is intended to be used with, so make sure, for instance, if you are building a PC that uses one of the latest Intel dual-core or quad-core processors, that the ATX12V 2.0 power supply has an additional 8-pin power connector that connects to the motherboard if the make/model of motherboard requires it, because not all current ATX12V 2.0 power supplies provide one.

However every ATX12V 2.0 power supply has the additional 4-pin power connector that is required for AMD Athlon 64 single-core and dual-core processors. Keep reading this page for more information on the power requirements of the different types of components.

Examples of a first-class power supplies that provide both of the additional 4-pin and 8-pin power connectors are the Zalman ZM-460-APS 460W unit, the Cooler Master iGreen Power 500W unit, and the Seasonic S12-430 430W unit.

You can make use of the Google search box at the top of this page (with its Web radio button enabled) to find local vendors and reviews of any of the products mentioned above.

Power supplies are often recommended or ridiculed on computer forums.

ATX is a power standard as well as a motherboard standard, as is the new BTX (Balanced Technology Extended) standard, which will eventually replace the ATX standard for power supplies and motherboards.

In June 2007, AMD announced its own DTX form factor, which is similar to Intel's BTX form factor.

Watch the following video if you want to see a demonstration of how to install an ATX power supply in a case and connect its cables to the devices to an ATX motherboard and inside the computer.

How to install a Power Supply [the power connectors for the various devices - motherboard, Molex, SATA hard drive, PCI Graphics card, etc., are shown/discussed] -

http://uk.youtube.com/watch?v=xvClS_M-09o

Expert Reviews - Latest PSU reviews -

http://www.expertreviews.co.uk/psus

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

Paul Mullen, who was 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 best way to choose RAM memory for a brand-name desktop or laptop computer, or memory for a paricular make/model of PC motherboard is to make use of the Crucial Memory Advisors (provided under the brief guideline on the minimum memory requirements for Windws XP, Windows Vista and Windows 7). If the Crucial memory you receive does not work, you are guaranteed a refund and standard shipping is free.

The memory requirements of the versions of Windows Vista and Windows 7

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. Note that if you are using a 64-bit version of Windows, up to 4.0GB, it requires twice the amount of memory as a 32-bit version, which can only use a maximum of about 3.5GB. For more information on computer memory, read the RAM pages of this site, which includes information on the lower memory requirements of Windows 7.

How to Use the Crucial Memory Advisor

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.

Note well that if you are upgrading a computer that is only a few years old by installing new processor, motherboard, RAM, video card, etc., you must also upgrade the power supply unit, because the power requirements and the sensitivity to power fluctuations of the hardware have increased significantly, and it is likely that the 230W PSUs used in most systems then are inadequate now - especially if it is not a unit of high quality. Moreover, current hardware technology uses the different power lines of the power supply differently from earlier technology.

In electrical terminology, A stands for amps, which is a measure of current, V stands for volts, and W stands for watt, the unit that is a measure of power output, which is calulated by multiplying the amperage in amps by the voltage in volts.

The power supply takes the 230V power (115V in the US) from a mains socket and transforms it into power at the voltages that the various components in a PC use. The different components in a PC can require different voltages, which means that a power supply must be several power supplies in one unit. Each separate supply is called a rail or a line. Every power supply has three main rails - the +3.3V, +5V, and +12V rails, plus two secondary -5V and -12V rails as standby rails.

Each rail has a maximum rated current, which is measured in amps (A), that it can provide. Since the amps x volts = watts (A x V = W), and power is measured in watts, each rail's voltage multiplied by its amperage gives the maximum amount of power that it can deliver. However to determine the maximum power output of a particular power supply isn't a matter of adding up the maximum output of all of its rails, because no power supply can supply its rated maximum on every rail at once. Therefore, a rail has a maximum combined wattage (the maximum power that it can deliver when all of the other rails are also working to full capacity), and the sum of all of those maximum outputs gives the power supply unit's maximum output in watts.

The maximum amperage delivered by the +12V rail(s) of a power supply unit (PSU) is of particular importance with modern high-performance systems. The power supply unit itself always has the power details of its different rails printed on it. Visit Jeantech's site and look under the Products heading if you want to see what the technical specifications for several ATX12V 2.0 PSUs are.

Some of the latest power supplies have up to four +12V rails, which can be useful in computers that have very powerful components, because if one component suddenly demands its rail's maximum power output, the other components on the other +12V rails can still draw enough power to keep going. However, note that splitting the amperage across up to four rails also increases the likelihood that one rail might be overloaded while the other rails have power to spare.

Most motherboard manuals tell you what the amperage of the +12V rail/rails have to be in order to power the motherboard properly.

For example, the manual for the MSI RS480M2-IL motherboard, which has an inbuilt video chip and therefore doesn't require a video card to be installed, says that the +12V rail must supply at least 18A (amps) of current. Many cheap off-the shelf PSUs provide only 15A or less of current on the +12V rail, and therefore can't be used with that motherboard if you want a stable system.

If you want to install a high-end video/graphics card the +12V rail would have to deliver between 20A and 30A. Therefore, you should always make sure that the PSU in a system can match the power requirements of a high-end video card before you buy or install it.

For example, at the time of writing this it is the middle of June, 2005, and nVidia has just released its long-awaited 7800 GTX graphics chip. A single video/graphics card using the chip requires the minimum of a 400W PSU with a +12V rating of 26A, while the SLI, dual-card configuration, requires a 500W PSU with a +12V rating of 34A as the minimum. Most standard PSUs don't usually deliver either 26A or 34A on the +12V rail, so a special PSU is required to run both of those options.

Note well that if you are going to install a power-hungry graphics card (or cards), to make sure that your computer can deliver the required power, you should visit the card manufacturer's site for information on recommended power supplies.

Remember that some power supplies now have as many as four +12V rails/lines in order to split the output. However, note that splitting the amperage across up to four rails also increases the likelihood that one rail might be overloaded while the other rails have power to spare.

Here is a review of a power supply that has dual +12V rails:

Foxconn's Next Power Play: FA-550 Power Supply Review -

"We do know of another power supply with 38A available to 12V that has received nVidia's SLI certification for a pair of power-hungry 7900GTX [graphics] cards, but that other power supply does so using a single rail. Splitting the amperage across two rails increases the likelihood that one rail might be overloaded whilst the other has power to spare." -

http://www.sysopt.com/features/cases/article.php/3614196

High-end PCI Express video/graphics cards have to be connected directly to the PSU. The following site shows examples of the PCI Express power connector. - http://www.jeantech.com/

If a particular power supply doesn't have a PCI Express connector and one is required of it, it's possible to buy an adapter that is fitted to a standard power connector of the kind that fits to standard IDE ATA (non-SATA) disk drives.

Here is a video review of a power supply:

Nexus 80 Plus Power Supplies [Video review] -

http://www.tomsgames.com/us/site/../nexus_80_plus_power_supplies.html

The full-sized ATX power suppy unit (PSU) that is found in most mid-tower cases uses a form-factor called PS/2. Smaller power supplies are generally found in micro-ATX cases and some OEM mid-tower cases. The most common smaller size is SFX, as found in emachines, Hewlett Packard, and Gateway micro ATX systems. A larger supply called PS3 is most commonly found in Hewlett Packard’s mid-tower cases. It has the same width and height as a standard PS/2 power supply but has reduced depth (3.5 inches, compared to 5.5 inches for a PS/2 power supply).

Quality power supplies have thermal and overload reset protection, but units of lower quality make do with only the protection of a fuse, which is more effective at preventing a fire than protecting the system. Moreover, the manufacturers of most of the cheaper power supplies solder the fuse into place in the hope that the unit will be replaced instead of just the fuse should it be blown.

The clusters of wires to the left and right of each unit (shown in the image of two power supplies at the top of this section of the page) have the various Molex plugs (or headers) on their ends that are required to connect drives, the motherboard, heatsink and fan units, and sometimes even adapter cards, such as some FireWire cards, etc., to the power supply.

If you run out of Molex drive headers, you can use a Y power splitter, which adds two headers by plugging it into one header, but, because they can put a greater load on the power cable than it was intended to carry, they should only be used to power devices that don't draw much power.

Newer power supplies all have the ATX 12V header introduced for use with Pentium 4 motherboards. Such power supplies are often labelled as being "Pentium-4 Compatible", even though they work with other ATX platforms, such as Socket A, Socket 754, Socket939 and Socket AM2 motherboards that run AMD's Athlon XP and Athlon 64 processors.

Power headers for Serial-ATA (SATA) hard disk drives have recently become available on some power supplies, so no adapter cable is needed to power them. Some power supplies also even have a tachometer output for connection to a motherboard’s fan header. See the image of two SATA adapter cables below. The white plug fits into a power cable connector from the standard ATX power supply and the black plug fits into the SATA hard disk drive:

The kind of SATA connector shown above does not provide a +3.3V connection, but some new SATA hard disk drives require this voltage. If so, only one of the new ATX12V 2.0 power supply units can provide it. ATX12V 2.0 is the new power supply standard that is going to replace the ATX 1.3 standard. The black 3.3V SATA connector, shown in the image below, is available in straight and angled versions, and comes directly from the ATX12V 2.0 power supply unit so that a conversion cable of the kind shown above is not used. The cable on the right has SATA written on its plug.

See the image below of the new ATX12V 2.0 standard, which has a 24-pin plug (right) that connects to the motherboard, whereas the ATX 1.3 standard uses a 20-pin plug (left).

By using adapter cables or special ATX connectors with 20 or 24 pins, the new power-supply specification can be made compatible with the earlier power-supply standard. Therefore, should an old power supply fail, a new replacement using the new standard can be used with the earlier hardware.

Some power supplies can be used with both 20-pin and 24-pin motherboard connectors. The 24-pin plug has a 4-pin plug that can be detached so that it can be fitted to a 20-pin motherboard power connector.

AMD Athlon 64/Phenom and Intel Pentium 4/Core 2 Duo/Core 2 Quad processors require a motherboard with a power supply with an extra 12V connector that is connected to a 4-pin header on the motherboard, as shown in the image on the right. Some motherboards have an 8-pin 12V connector. You have to have a power supply that provides the 8-pin connector to use it with such a motherboard.

All fairly recent power supplies have the extra power connector. However, if you have a power supply that doesn't have the extra connector, and which also supplies the correct maximum amperage that can be delivered by its +12V rail (or rails, because some of the latest power supplies have up to four +12V rails), you can't use it to power the above-mentioned processors.

As you can see, the keyed connector can only be connected one way to the motherboard. The hook on the connector fits over the protrusion on the header on the motherboard.

Some power supplies have a connector that splits so that it can have 8 pins or just 4 pins. The animated image below shows such a connector.

Examples of a first-class power supplies that provide both of the additional 4-pin and 8-pin power connectors are the Zalman ZM-460-APS 460W unit, the Cooler Master iGreen Power 500W unit, and the Seasonic S12-430 430W unit.

****

It can be very frustrating if a power supply's cables are too short to reach the top or the bottom drive installed in a case, or if the ATX power leads don’t reach to the motherboard when, say, it's installed in a full tower case. Lead extenders are available, but it's always best to buy a fully satisfactory power supply in the first place. Most quality brands of power supply provide plenty of cable length, while many of the cheaper brands do not.

The image below shows the inside of a standard ATX case without any of the components installed. One of the side panel's has been removed. The power supply, with the power cables coming from it, can clearly be seen in the upper left hand corner. The case fan with its cable is just below it. The drive bays are in the upper right hand corner, and below them are the cables that come from the front of the case for the LED lights, the Reset switch, and the Power-on switch, etc. These will be connected to the appropriate block of connection points on the motherboard. For a diagram of the connection block on the motherboard, see this Build a PC page on this site.

Buy a quality case, because unless you know how to use electronic testing equipment, the only way to find out if a problem has to do with the power supply is to install the same hardware in a different case, or a different set of hardware in the same case.

Note the size of the power supply in the ATX case shown above. It is small, and, as such, will allow unhindered access to the motherboard, which is fitted close to the unopened side. All good quality power supplies are this size nowadays. Do not purchase a case if it has a large, light, square power supply, because it is likely to be cheap, old technology.

It is difficult for non-specialist people to determine the quality of a particular power supply unless they rely on brand names of the manufacturers that are known to produce quality units, such as Antec and Enermax. But the well-known manufacturers are not the only producers of quality power supplies. There are many relatively unknown manufacturers that produce units of quality.

Moreover, a poor-quality power supply doesn't have to be large, it could also be as small as a high-quality unit. So, a good rule of thumb to use is this - better quality power supplies tend to be heavier than those of lower quality. If you take the power supply out of the case and weight it, it should not weigh less than 3lbs (1.4Kg), otherwise it is probably not adequate to meet the requirements of a modern system.

Visit Anandtech for reviews of cases.

Also use the Google search box at the top of this page, with its Web radio button enabled, to search for terms such as "atx cases", atx + cases, "pc cases", etc., or enter the make and model of known cases to obtain reviews and information about them.

Click Build Your Own PC for more information on cases on this site.

The better the quality of all of the components in a computer the less the likelihood of system failure. Of particular importance in this regard is the quality of the motherboard, case, power supply unit - and the heatsink and fan fitted to the processor, which should be checked regularly, because even quality units are prone to failure.

Some motherboards monitor the system's fans, and the processor temperature, and the BIOS setup can be programmed to produce an alarm if the fans fail and the processor temperature reaches a certain level. Even with a such a motherboard, you should still check the processor fan regularly just in case the monitors themselves are not working.

Low quality components almost always means trouble and expense sooner rather than later. Especially if you have to rely on the services of an expensive technician, etc. If, say, the power supply blows out, or fails while your hard disk drive is working, the chances of that drive being ruined are excellent.

If you are purchasing a new computer, or building your own, it would be worthwhile obtaining advice about the quality of the components from a respected source, unfortunately not usually the high-volume suppliers of computers. A small computer shop that has been in business for many years is usually a better source of information. It is also a good idea to subscribe to a good PC magazine, such as PC Pro (UK) and to visit a good online PC magazine such as PC Pro and Expert Reviews. There are also plenty of websites that provide this kind of information free of charge. You can make use of the Google search box at the top of this page (with its Web radio button enabled) to conduct searches with suitable search terms.

Different uses can require a different style of case. Moreover, no single type or size of case has universal appeal. However, since they arrived on the scene many years ago, the mid-tower cases have been the most popular, probably because, for the vast majority of users, the purchase of a mid-tower case is the correct choice.

Removing an old power supply and installing a new one is a relatively simple task . You just remove four screws at the back of the case that secures the existing power supply unit in the case, remove the cable that goes to the motherboard and any of the components (hard drive, CD/DVD drive, graphics card, etc., take it out and then screw the new power supply in so that it connects to the same components. If you need instructions, here is a page that provides them:

Installing a power supply unit -

http://www.computerhope.com/issues/ch000422.htm

If you want to find out about the technical details of how a power supply works, visit this article. -

How Power Supplies Work -

http://computer.howstuffworks.com/power-supply.htm

See this page of the above article to view a table showing the range of the power requirements in watts of the main components in a personal computer. -

http://www.howstuffworks.com/power-supply3.htm

****

TOM'S HARDWARE GUIDE: Articles on power supplies

Power Supply Roundup: Part II : Our Second Round Of Mainstream PSUs -

http://www.tomshardware.co.uk/power-supply-roundup,review-31413.html

Tom's Hardware Guide has dropped many of its articles, so there is only one article linked to here at present.

Silent PSUs: Fortron Versus Silverstone : Passive Power Supplies In The Lab -

http://www.tomshardware.co.uk/Power-Supply-Efficiency,review-31270.html

PSUs: More Important than You Think -

http://www.tomshardware.co.uk/psu-power-supply,review-2385.html

5 Power Supplies Get the Full Juice Treatment -

"We give five new power supply units the full juice treatment after our previous stress tests laid many supposedly high-end units to rest in the scrap heap. Did vendors take heed of the hard lessons they learned during our past tests?" -

http://www.tomshardware.co.uk/...review-1586.html

Power management

APM and ACPI are the two distinct power-management standards encountered when dealing with PC systems running Windows. The differences between the two standards can be confusing even to an unsuspecting troubleshooter who is fully aware of how often power-management issues can be the causes of system failures.

All computers currently have a BIOS setup program - usually entered by pressing the Del key after the start-up memory count - and most BIOSes have a page devoted to Power Management settings. Therefore, if you are experiencing problems that may be power-related, such as shutdown problems, the first actions to take would be to disable the power settings in Windows (in the Control Panel) and in the BIOS.

Superseded motherboards that use slotted processors

Thankfully, Intel and AMD no longer produce slotted processors (Slot 1 and Slot A respectively), because they are more difficult to install than socketed processors. As processors have increased in speed, they have become more difficult to keep cool. Socketed processors are easier to cool, so both AMD and Intel have reverted to them.

A boxed slotted processor will come with installation instructions, but if you buy a bare processor you will have to know how to install it.

Slotted processors come with two support arms that are already screwed into both ends of the processor's slot to support it in an upright position. They also either make use of a passive heatsink (no fan) that fits to one side of the processor's case, or a heatsink and fan unit that also fits over one side of the processor's case. Both units look like something dangerous.

Click the thumbnail image below to see a full-size image of an Intel Slot 1 motherboard with an Intel Pentium 3 processor that has a passive heatsink attached to it. - Use your browser's Back button to return here.

[Click to enlarge]

If you need to find out how to install a Slot 1 (Intel) or Slot A (AMD) processor, try using the Google search box at the top of this page. Try a search phrase such as: install + "slot 1" + processor.

A Slot 1 motherboard

Click the thumbnail image below to view the full image of an Abit BE6 Slot 1 motherboard fitted with 450MHz Pentium 3 processor. A heatsink and fan unit is attached to the near side of the processor, and the three SDRAM DIMM memory slots are fitted with 128MB PC100 DIMM modules. - Use your browser's Back button to return here.

[Click to enlarge]

Note well

Note well that you should make sure that you purchase a cooling unit specifically made for the type of processor you are using. If a cooling unit is designed to be used with only one particular make or with both Intel and AMD processors, that information will be included in its list of technical specifications.

If you want to see which manufacturers produce quality cooling hardware, visit www.overclockers.co.uk/. Click here! to go directly to cooling sites listed (on the third of four Links pages on this site) under Overclocking and Cooling Info Sites.

A motherboard always supports only a dedicated range of processors

Always remember that the motherboard must support a particular processor. For example, the Elite K7VZA motherboard (Elite Group - www.ecsusa.com/), only has a 100MHz system bus (FSB) frequency, so it will only support the 100MHz version of the 1.2GB AMD Athlon processor. There is a 133MHz version of this processor that will run on Athlon-compatible motherboards with a 133MHz FSB frequency setting that is usually either enabled by setting motherboard jumpers, DIP switches, or via the BIOS.

At one time, a particular Socket 7 motherboard supported processors made by Intel, AMD, and Cyrix/IBM, but now a particular motherboard may or may not support VIA processors, but will only support Intel or AMD processors, never both.

Tip. - Take care when installing the heatsink and fan over a socketed processor. The processors look very solid and durable, but they can easily be cracked or broken by rough handling.

Software drivers: Updates

Updated software drivers for a particular chipset can be downloaded from the manufacturer's website (Intel, VIA, ALi, etc.), the motherboard manufacturer's website, or from sites that provide drivers, such as the list of them provided on the first Links page of this site.

These software drivers will be used to drive the system's IDE or SATA hard disk drives and CD/DVD drives, the AGP bus, and the USB Controller. They are frequently updated to make improvements and remove bugs, so it is well worth downloading and installing them.

There are occasions when a driver update causes more problems than the version it replaces, so it is always a good idea to read the postings in the motherboard's ALT newsgroup (more information is given about newsgroups further on in the article). Any difficulties experienced by owners of systems with your motherboard will come to light there in postings, and suggestions about what to do to remedy any problems will also be posted.

More relevant motherboard information

Disk-drive cables

Go to http://www.pcguide.com/ref/hdd/if/ide/confCable80-c.html to read an article on the differences between the 40-conductor ATA 33 IDE ribbon cable and the newer, higher quality 80-conductor ATA 66 ribbon cable, which supports error correction, and can be used for any ATA hard drive, including ATA 33 and ATA 100 hard disk drives - even if that drive does not support error correction.

See this page of the Build a PC article on this site for information about the new round IDE cables.

Click here! to go to information on this site on the new serial SATA disk-drive standard, including images of the cables that it uses.

Motherboard ports

The motherboard itself will usually be fitted to a removable tray fixed up against one side of an ATX tower case in one way or another, so that the adapter/expansion slots are properly aligned with their outlets at the back of the case. Because expansion/adapter cards are fitted at right angles to the motherboard, the rectangular ports to which the peripheral devices, such as the monitor, are attached, will be horizontally aligned at the back of the case.

Many motherboards coming out now have done away with all of the legacy ports (PS/2 mouse and keyboard ports; parallel port, etc.), and have replaced them with USB and FireWire ports.

The ATX Abit AT7 motherboard - available on both the Athlon (Socket A/462) and Pentium 4 (Socket 478) platforms - is such a motherboard. The ports on the motherboard are shown in the image below. -

From left to right are the two USB 1.1 ports, two USB 2.0 ports, a pair of IEEE1394 FireWire ports, full analog 5.1 audio out, digital audio out (five round and coloured ports), and LAN (network) ports (far right).

There are no legacy ports, so, with this motherboard installed, unless you obtain conversion plugs that are available (see the USB page of this site for images of them and more information), you would not be able to use a printer that only has a parallel port, a PS/2 mouse or keyboard, a serial external modem, or any device such as a joystick that uses a serial port. You can only use USB or FireWire devices.

Below is the ports panel of a motherboard with USB and FireWire ports that retains PS/2 mouse and keyboard ports (far left), the parallel port (red), and, below it, a single serial port. The round coloured ports belong to the incorporated sound chip, and the two blocks on the left and right with three ports each incorporate a single FireWire port each (top), and two USB ports.

As shown in the images at the beginning of this article, ATX cases are fitted with a removable ports panel that often has metal cut-outs in it that are themselves removed so that the ports on the motherboard fit through them. You remove the cut-outs in the ports panel that match the ports on your motherboard. For instance, you would not remove the cut-outs for an inbuilt video card port or for a sound card's ports if the motherboard does not have inbuilt video or sound ports. The ports panel that comes with a new motherboard usually doesn't have the openings for the ports covered with cut-outs, because all of the ports on the board match the openings on the ports panel, so that no holes will be left that might reduce the cooling of the inside of the case.

As you can see, the Abit AT7 motherboard has a port profile that is completely different from the standard ATX legacy motherboard's port profile shown above it. Luckily, this motherboard comes with a ports panel that matches its unique port profile, but that might not be the position with other motherboards - especially if purchased second-hand. In that situation, you would either have to buy a case that comes with a port face plate that matches the motherboard's port profile, or you would have to install the motherboard with the port face plate removed. So, always check the position regarding the ports panel before you buy a motherboard.

The thumbnail images above are views of a desktop tower computer case. The large vertical slot on the case, above the horizontal slots, is the cutting for the ports built into the motherboard. The motherboard itself will be fitted along the right side of the case. This is a standard ATX case that will accept standard ATX motherboards. If it was a case that was made for motherboards that use a riser card (fitted in a slot at a right angle to the motherboard) to fit adapter cards, the adapter slots (fitted at right angles to the riser card) would be vertically instead of horizontally aligned at the back of the case.

The use of a riser card makes it possible to use a case that is much slimmer than a standard ATX case. Indeed, it is almost certain that slimline desktop and tower cases have to be fitted with a riser card.

There is information further down on this page about why non-standard ATX cases and motherboards that make use of riser cards should be avoided.

A Super Socket 7, AT form-factor motherboard - now superseded, but still in use, which uses Intel MMX, AMD, and Cyrix/IBM processors, differs from a Slot 1 motherboard for (Pentium II and III CPUs) in having a large square, usually white, ZIF Socket for the processor - and the Level 2 cache chips on the motherboard itself instead of being built into the processor's case.

The motherboard shown in the thumbnail image (above left) is the VA-503+ from FIC, a Baby-AT form-factor, Super Socket 7 motherboard, with a VIA Apollo MVP3 chipset, that can be powered by Intel MMX, Cyrix/IBM M1/M2, and AMD K6, K6-2, and K6-3 processors. Baby-AT boards are housed in AT cases that have been superseded by ATX cases. The white ZIF (Zero Insertion Force) processor socket is in the bottom left-hand corner of the motherboard, as shown in close-up in the image on the right, in which the brown insertion/extraction lever is more clearly visible down its left-hand side. The VIA MVP3 chipset, consisting of two chips, can clearly be seen above the ZIF Socket, with the BIOS chip's battery between them. An Award flash BIOS chip with its silvery sticker can be seen in the upper left-hand corner of the board. There are three black ISA slots, three white PCI slots, and an AGP slot next to the last PCI slot.

On this motherboard, the banks of configuration jumpers can clearly be seen coloured blue.

The two thumbnail images, above, which show DIP Switch blocks on a motherboard (right), sometimes used to configure its settings, and a block of jumpers (left), which are found on most motherboards, including those that make use of the BIOS setup program to set the hardware configurations. You should be able to find out how to place the jumpers and set DIP switches in the motherboard's manual.

Overclocking a processor, RAM and graphics card

To overclock the processor(s) of a PC means to run it faster than its stated running speed (frequency). For example, if you can increase the motherboard's speed settings, which are usually set in the BIOS setup program, so that a 2.0GHz processor runs at a speed of 2.5GHz, it has been overclocked by .5GHz (500MHz).

It is also possible to overclock the RAM memory, which is usually overclocked by increasing the motherboard's FSB, and graphics card.

BIOS Flash - Overclock Your Graphics Card in 5 Minutes -

"3D drivers and third-party utilities let you overclock your graphics card's GPU and memory. Its pixel shader clock speed can only be changed in card's BIOS, though. This makes the changes permanent and independent of the graphics driver..." -

http://www.tomshardware.co.uk/...review-29744.html

Information on motherboard/processor settings is provided further down this page.

Note that some motherboard manufacturers, such as MSI, have developed automatic overclocking technology that overclocks the system automatically.

The MSI K9A2 Platinum (AMD Socket AM2+) motherboard provides this technology. The following is an extract from its user manual.

"Dynamic Overclocking Technology is an automatic overclocking function, included inthe MSI ’s newly developed Dual CoreCenter Technology. It is designed to detect the loading of CPU/GPU while running programs, and to over-clock automatically. When the motherboard detects that the loading of CPU is exceed the default threshold for a time, it will speed up the CPU and fan automatically to make the system run smoother
and faster. When the graphics card detects that the loading of GPU is exceed the default threshold for a time, it will speed up the GPU, memory, fan and voltage automatically to make the system run smoother and faster. When the CPU/ GPU is temporarily suspending or staying in low loading balance, it will restore the default
settings instead. Usually the Dynamic Overclocking Technology will be powered only when users' PC runs huge amount of data, like 3D games or video process, and the motherboard/graphics card need to be boosted up to enhance the overall performance."

October 9, 2008 - The Asus P6T Deluxe motherboard supports the new Intel Socket 1336 Core i7 processors that are to be launched in November 2008. The board is ready for the market and has been distributed to reviewers world-wide. It allows overclocking on the fly by making use of a device attached to a USB port. You can see an image of the device on this page:

New ASUS P6T DELUXE with Super Hybrid Engine Delivers Maximum Overclocking and Energy Efficiency -

"The P6T DELUXE adopts the usage of TurboV—an advanced overclocking tool that utilizes a micro-controller to provide precise overclocking adjustments, and allow users to conveniently adjust the CPU ratio (multiplier)* for instant CPU upgrades for real-time performance enhancements. TurboV can also provide adjustments to the NB voltage, NB-PCIe voltage, CPU PLL voltage and DRAM voltage in 0.02V micro-intervals." -

http://www.asus.com/news_show.aspx?id=12949

Apart from that page, there is no other information on the board on the Asus site yet. To locate reviews of this motherboard enter asus p6T deluxe in the Google search box at the top of this page (with its Web radio button enabled).

Note that Intel's latest Core i5 and Core i7 processors have a feature called Turbo Boost that automatically overclocks the processor.

About the New 2010 Intel® Core™ i5 Processor -

http://www.intel.com/en_UK/consumer/products/processors/...

Explaining Intel's Turbo Boost technology -

http://news.cnet.com/8301-13512_3-10362882-23.html

Here are some webpages that should get you well on the road to knowing about the art of processor overclocking, which you must investigate thoroughly before indulging in it yourself:

Beginner's Guide to Overclocking for Performance … and Value! -

http://www.sysopt.com/features/cpu/article.php/3608801

Make your PC go faster for free - "It may sound daunting, but overclocking your PC is actually quite simple - and, as Antony Leather explains, it can give your system a real power boost." - http://www.expertreviews.co.uk/features/259888/...

How To: Overclocking Your AMD Processor : Introduction: The Basics Of Overclocking -

http://www.tomshardware.co.uk/phenom-overclock-athlon,review-31518.html

Don't try this at home: AMD overclocks new Phenom II X4 to 7 GHz -

"While 7 GHz was achieved with extreme cooling, AMD says overclocking up to 3.8 GHz for the 3.2-GHz X4 955 is safe at home." -

http://www.computerworld.com/action/article.do?...

Overclocking Core i7: Power Versus Performance : Does it Make Sense To Go for Maximum Performance? -

http://www.tomshardware.co.uk/overclock-core-i7,review-31553.html

Overclocking: Core i7 Vs. Phenom II -

http://www.tomshardware.co.uk/overclock-phenom-ii,review-31487.html

Ultimate Budget Overclocking Box - A 3.5 GHz Core 2 System with a €49 CPU -

Intel’s Pentium Dual-Core offers heretofore unseen overclocking potential which transforms this inconspicuous “low-cost CPU” into a very potent and much faster middle class CPU with the right settings. Many buyers aren’t sure what to make of the Pentium Dual-Core when they see it selling for €49. The “Pentium” in the name may lead some to believe it is related to the old (P4) Netburst micro-architecture. In reality, though, this is nothing more than a marketing trick to differentiate the low cost CPU from the more expensive Core 2 line...." - http://www.tomshardware.co.uk/...review-29816.html

Yorkfield at 5 GHz with Water Cooling? -Is 45nm An Overclocker's Dream? -

"Intel’s Penryn family of 45 nm processors is making waves, but still hasn’t had much desktop market penetration, because the firm has so far only released the expensive "Extreme" QX9650 model. As enthusiasts look forward to upcoming lower-cost versions that will give them the best "bang for the buck", a few extreme overclockers have already pushed these beyond 6 GHz using equally extreme below-ambient coolers..." -

http://www.tomshardware.co.uk/Yorkfield-overclocking-5ghz,review-29809.html

Sibling Rivalry - Intel E6750 and Q6600 Overclocking Duel -

"In general, we can say that overclocking definitely pays off, regardless of whether you choose the dual-core or the quad-core CPU. Either one of these processors is capable of a 25% speed increase, which is noticeable even with everyday computing tasks. The increased energy cost that results from overclocking is not especially pronounced with Core 2 processors – their share in the system’s overall power consumption is so small that overclocking always pays off. The question whether you should opt for a dual-core or quad-core processor is easily answered as well..." -

http://www.tomshardware.co.uk/Intel-E6750-Q6600-MSI-Gigabyte,review-29731.html

Overclocking to new limits: Testing the new Core 2 Stepping -

"Intel recently introduced its latest flagship model, which also happens to be the fastest quad-core x86 processor. THG ran the new processor series through its paces, carrying the internal designation G0 stepping, and tested its overclocking potential – with unexpected results." -

http://www.tomshardware.co.uk/overclocking-intel,review-2395.html

Budget Overclocker - AMD's Athlon 64 X2 5000+ Black Edition -

"The “Black Edition” of AMD’s Athlon 64 X2 5000+ features an unlocked multiplier. Unlike the first Black Edition model, the 90nm 6400+, the new processor is even produced on a 65nm process. As a result, it only draws about half as much power as the 6400+ and offers enormous overclocking potential. Pushed to its limit, this processor is faster than an Athlon X2 600+ or Intel’s Core 2 Duo E6550. Among today’s CPUs, this €110 processor is unique in that its performance can be increased without having to raise either the FSB or the memory frequency, making it a safe choice for any AM2 board..." -

http://www.tomshardware.co.uk/Athlon64-X2-5000-Black-Edition,review-29679.html

Extreme FSB: Taking the E6750 Beyond 4 GHz -

"Intel promises noticeable performance gains from its new FSB1333 bus, currently available on Core 2 series 6x50 processors." -

http://www.tomshardware.co.uk/...review-2373.html

System Builder Marathon (Overclocking) Day 1 -

http://www.tomshardware.co.uk/Overclocking,review-2355.html

Overclocking Marathon Day 2 - A Home Brew -

http://www.tomshardware.co.uk/Overclocking,review-2358.html

If you want to find out more about overclocking a processor (or video card), click here! to go directly to relevant links provided on the third of the four Links page on this site.

Note - make sure that you do as much research as possible before overclocking a particular processor, video card, or RAM. There are overclocking newsgroups, and a wealth of overclocking sites. By following links on the third of the four Links pages on this site, or by entering overclocking in the Google search box at the top of this page (with its Web radio button enabled), you'll be able to find out how other people have overclocked that particular processor - successfully. You need to do this, because it is possible to destroy a processor if you overclock it too far.

Here are the most popular makes of motherboard used by the overclockers recorded on the SysOpt Overclocking Database on 27 May 2006. The figures are the numbers of each make of motherboard used by the participating overclockers. The first five places were the same in October 2003. Since then, ECS has moved from 8 to 6. IWILL has moved from 6 to 7, and Intel and AOpen have swapped positions. Intel was 10 and is now 9. Intel didn't used to want to produce overclocking motherboards that overclocked Intel processors, but that situation seems to be changing. Surprisingly, the Intel D975XBX motherboard provides comprehensive overclocking support that matches the offerings of similar Pentium motherboards from Asus and Gigabyte.

Computer forums

There are many sites that provide PC forums that are either live or conducted via text messaging. Problems and advice is often provided by people who have had direct experience of hardware and software issues.

Click here! to go to a list of many other links to computer forums on the first of the four Links pages on this site.

You can also find many more forums on your own by entering search words such as "pc forums" or "computer forums" or computer + forum in the Google search box at the top of this page.

The proper support considerations when evaluating a motherboard, either in a new computer, or as an upgrade

The selection of a motherboard can have a marked effect on a PC's reliability. The motherboard can be the difference between a stable, reliable machine, and endless crashes.

By becoming familiar with the different parts of a PC's hardware and software, you will easily be able to make an informed choice. This site contains all of the information in the form of articles or links to other information that you will need to gain that knowledge. My advice is to keep reading until everything falls into place of its own accord.

I am assuming that you are building your own computer or upgrading an existing one. The questions you need to find answers for are as follows:

1. - Does the motherboard support the type of processor (Intel or AMD) and RAM that you want to use? And does the form-factor of the case match the form-factor of the motherboard?

For example, a standard ATX AMD Athlon motherboard can be installed in any standard ATX case, but a specially designed ATX case is required for a Pentium 4 motherboard.

If you are upgrading a brand-name PC, you might only be able to install a customised non-standard motherboard in its customised non-standard case. The manufacturer might be able to supply the upgrade. If not, you will have to buy a standard case and motherboard.

2. - Does the motherboard's manufacturer have a website that provides BIOS and device driver updates, which is frequently updated to cover other support issues, such as operating system, hardware, and software compatibility?

Visit the BIOS page of this website for information on the BIOS setup program.

Hardware includes, RAM (SIMMs/DIMMs/RIMMs), hard disk drives, ports (serial/parallel/USB/FireWire), video cards (ISA/PCI/AGP), etc.

For example , most hard disk drives purchased new now use the IDE ATA (UDMA) 100 or 133 mode, while the BIOS and motherboard's chipset might only support ATA (UDMA) 33 or 66 modes, perhaps making it necessary to install a software patch from the drive's manufacturer to disable ATA (UDMA) 100 mode so that the UDMA 33 (or 66) mode can be used instead. But, most of the time, all you have to do is install any ATA (UDMA) drive to a motherboard that supports any ATA mode, and it will work at the highest mode supported by that motherboard and operating system, even if the drive itself can work in an even higher mode, such as ATA 100 or 133.

The first FAT16 version of Windows 95 only supports hard drives and drive partitions of 2GB.

3. - Is the power supply unit (PSU) adequate to power the devices being installed, or to accommodate upgrades?

For example, emachine PCs usually have very low-powered power supplies that are barely adequate to run the hardware, which usually have their video and sound chips incorporated on the motherboards. You would not be able to upgrade to a video card without also replacing the power supply.

For more information on this site about the two modes of operation of hard disk drives (ATA (also known as UDMA), and SCSI), click Disk Drives, and Technical Stuff.

USB/FireWire support

Note that, depending on your requirements, you should also know about USB and FireWire support in order to make the best choice of motherboard.

The settings

The motherboard settings shown below, set either via the BIOS setup program, or by jumpers or DIP switches on the motherboard itself, should be indicated and explained in the motherboard's user manual, which is provided with a retail, boxed motherboard, or can usually be downloaded for inspection from the manufacturer's website.

The speed of a processor (the core frequency) is the product of the motherboard's front side bus (FSB) speed/frequency, and the clock-multiplier setting. The FSB is the the network of connections on the motherboard that run between its devices and chips, and the FSB speed/frequency is the frequency measured in MHz that it is set to run at.

See the RAM page on this site for information on how the FSB relates to the effective, as opposed to the actual speeds at which DDR RAM runs.

The I/O voltage is fixed and is usually unchangeable.

The variable core voltage can be set according to the requirements of the processor. On reputable motherboards, the range of settings can usually be altered in increments of .1 of a volt. The latest Intel and AMD processors use less voltage than the K6-2 and K6-3 processors, because the latest manufacturing processes can put more circuitry in much less space, but they use more power because they work at much higher speeds/frequencies. That is why cooling and protection from overheating is of such importance now.

Poor or cheap motherboards can come with very limited settings for bus frequency, the clock multiplier, and the core voltage. That is why it is very important to find out what the range for each is before you buy a new computer or motherboard. Small increases in these settings can often cure an unstable system. This can be done by implementing the settings' information in the motherboard's manual.

AMD tests all of the most popular motherboards that have been designed to run AMD processors. The tests focus on three major areas of motherboard processor support: the BIOS, electrical, and software. A motherboard is only listed on the AMD's recommended motherboard list after it has passed all of the tests. Although there may be motherboards not included on this list that may function perfectly adequately with an AMD processor, AMD only recommends the designs that have been fully tested and passed by the company. You can find links to recommended motherboards on AMD's home page at - http://www.amd.com/.

Note that Intel's Pentium 3 and 4 processors, and the AMD Athlons and Durons, usually, but not always, have an onboard clock-multiplier that can be changed, but only by someone who knows precisely how to do it.

Toms Hardware has an illustrated article on how to unlock the clock multiplier by using a pencil on AMD Athlon and Duron processors.

The only easy alternative way to overclock those processors is to use a faster bus frequency (FSB) setting - from using the default of 100MHz to using, say, 112MHz or 133MHz - if the motherboard supports the faster speed.

You should be able to find out everything you need to know about its settings and how to overclock a particular processor from Overclockers.com. Click here! to go to links to overclocking sites on the third of the four Links pages on this site.

Take care! Gather all of the necessary information before you attempt any kind of overclocking. You can destroy a processor, and other hardware, if you take the settings too far over their default values.

Note that some motherboards are more overclocking-friendly than others, and some motherboards might not allow overclocking at all. Overclocking involves increasing the bus frequency (FSB), or increasing the clock-multiplier setting.

The following quote from the article above provides the reason why you usually have to choose a suitable motherboard and memory combination in order to overclock successfully.

"Some motherboard vendors don't lay out their products to use very fast DDR2-1066 RAM; the reasons for this have to do with the components they choose to populate their boards. These must be of higher quality to deliver clean signals to memory at such high speeds, which makes motherboards more expensive. Even printed circuit board designs play a significant role: data lines designed to run at 500 MHz can be placed very close to one another with lengths of up to almost 4 inches (10 cm). A bad design can cause capacitance build-ups and resonance to develop among circuits, which in turn can cause instability or crashes when clock rates are cranked up."

Here is a page that should get you well on the road to knowing about overclocking:

Beginner's Guide to Overclocking for Performance … and Value! -

http://www.sysopt.com/features/cpu/article.php/3608801

The Google search box at the top of this page with its Web radio button enabled can provide you with many links to sites that provide recommendations on how to choose a motherboard. Try using a search phrase such as: guide + choosing + motherboard (as is). If you want a motherboard that allows a wide range of overclocking settings, try a search such as: overclocking + motherboard + review (as is).

Future-proofing your investment - the considerations

For the maximum future proofing, it is therefore of the utmost importance for everyone to know the make and model of motherboard a computer has before purchasing it.

If you have access to the Internet, valuable information can be gleaned about motherboards from PC hardware sites, such as Tom's Hardware Guide. (Click here! for others.) If you don't have Internet access, it would be well worth your while to make use of an Internet cyber café to access this information. If a computer manufacturer's site doesn't provide the make and model of motherboard in a particular model of computer, you should be able to send in an e-mail request for the information. Obtaining a Hotmail e-mail account would be the best way to do this if you're using a cyber café.

Beware - many of the computer suppliers that advertise in newspapers and magazines often use cheap or no-name or old or integrated motherboards, which have very limited upgrade potential. That is why they don't name the motherboard in their advertisements!

Slimline desktop, and mini tower cases, or proprietary-make tower cases that use riser cards to attach sound, video, adapter, and modem cards parallel instead of at right angles to the motherboard, should also be given a wide berth.

Slimline and mini-tower cases severely restrict the expansion of the computer, and proprietary makes of case that use a riser card to attach expansion cards have specially designed motherboards which usually only that particular manufacturer will be able to replace - usually at a premium. At a future date, you will therefore not be able to install any of the much wider range of standard ATX motherboards.

Click here! to read about the low-profile video cards installed in slimline desktop cases that can be used by HP, Compaq, and Dell. Use your browser's Back button to return to this point on this page.

Whether or not a computer has a motherboard that uses a riser card can be determined from looking at the back of a tower case. If the rectangular attachment ports at the back of the case - the plug-in points on the backing plates of the ISA or PCI or AGP expansion cards - are horizontally aligned the computer has a conventional ATX motherboard. However, if all these ports are vertically aligned, then the motherboard uses a riser card. The case will usually be small and/or slim.

Do not buy a computer that has this kind of architecture unless you have no intention of upgrading it.

Note that the alignment will be the opposite of this on desktop cases, with a vertical alignment of the attachment ports indicating a standard motherboard. This is because the motherboard is fitted to the bottom of the horizontal case, and the ISA, PCI, and AGP cards are fitted at right angles to the motherboard, so the ports on the cards will be vertical.

All of this might sound complicated, but all you have to do is imagine how the motherboard fits vertically along one side of an ATX tower case, with the expansion cards at right angles to it. A riser card fits at right angles to the motherboard and the expansion cards are fitted to the riser card, at right angles to it, thus making them lie parallel to the motherboard so that their rectangular ports are vertically aligned.

You can easily work out the alignment of the ports on a desktop case, because a desktop case is really just a tower case lying on one side with the motherboard screwed to the bottom side.

AMR and CNR and ACR motherboard riser slots

Note that you should not confuse AMR and CNR and ACR riser slots on a motherboard with a motherboard that has to have a riser card fitted to it in order that ISA, PCI, or AGP adapter cards can be fitted to the riser card.

AMR stands for Audio Modem Riser, and CNR stands for Communication and Network Riser. The AMR slot on a motherboard allows a modem or the external interface for an integrated sound chip to be attached to the motherboard, and a CNR slot allows for both of those and a network connection. A CNR slot supports USB

ACR stands for Advanced Communications Riser and is a rival standard to CNR. ACR supports modem, audio, LAN, and DSL broadband Internet connections.

****

Dial-up modem cards (internal modems) are installed in an ISA or PCI slot in the motherboard. Or you can purchase an AMR modem that fits into the AMR (Audio/Modem Riser) slot on some but not all motherboards. AMR modems are more difficult to obtain than ISA and PCI modems, but they can usually be obtained by mail order. An ordinary ISA or PCI modem cannot use the AMR slot.

An AMR slot is usually found on the motherboards of budget PC's where manufacturers can use this slot to add modem and sound capability - cheaply. Unfortunately, anything that runs in this slot is completely run by the processor, and therefore hinders its performance. Unless you are looking to build a cheap Internet/Office computer, motherboards with this feature should be avoided.

Note that a CNR slot is a new type of slot that is one step above an AMR slot, because it also allows for the connection to a network. Short for Communication and Networking Riser, the slot is designed for reducing costs for OEM's that offer a home networking implementation, or audio and modem subsystems. Chances are you won't see anything for sale in this slot, since it is reserved for the use of PC manufacturers. It also suffers from the same issues as AMR slots, so high-end gaming computers and workstations will not have this slot on their motherboards.

As mentioned earlier on this page, the CNR and ACR standards are competing riser-slot standards. Although the CNR and ACR offer similar functions, the way in which the functions are implemented can be completely different:

ACR is backwards compatible with AMR, CNR is not. ACR provides support for DSL technologies via its Integrated Packet Bus (IPB) technology. CNR provides such support via USB. ACR provides for dual support for the LCI (LAN Connect Interface) and MII (Media Independent Interface) LAN network interfaces. CNR supports either of these interfaces, but not both at the same time. The ACR specification has reserved pins for a future wireless network interface, while the CNR specification has the pins available but will only define them when wireless network technology has become more established.

It's going to be left to the motherboard manufacturers to decide if the ACR specification's additional features are worth incorporating into their boards.

Google searches

You can enter the terms motherboard + amr or + cnr or + acr in the Google search box at the top of this page (with its Web radio button enabled) to find many webpages with information about these slots.

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PC Buyer Beware! Copyright © Eric Legge 2004-2010. All rights reserved.