OK, so you know it's important in the "grand scheme of things", and you're confident every computer's got to have one, but do you actually know which sort of motherboard your desktop PC contains? Chances are, you'd have to go and look it up.

You're not alone. When weighing up the components of a PC they intend to buy, most people first check the processor and clock speed, then the size of the hard drive, and will probably also have a peek at which graphics card is lurking inside. This is a perfectly legitimate way of sizing up a PC, but the motherboard is crucial, too. Often, however, when it comes to evaluating a system, the motherboard rarely gets a look in.

Those who are upgrading their existing systems, or building new ones may also look at the components they need to improve or optimise system performance, but will often forget the impact the motherboard can have on the whole package. For instance, your motherboard needs to be able to handle the type of expansion you require, such PCI slots, FireWire ports or Serial ATA (SATA) ports.

Never fear - PC World has put together this comprehensive buying guide on motherboards, to tell you what this mystery component is and how it functions. This guide is also designed to equip you with the criteria you need to choose the right motherboard for your PC setup.

What is a motherboard?

What is a motherboard?

Also sometimes referred to as the system board or main board, the motherboard is the physical board that houses the computer's basic circuitry and components, and is perhaps the most important feature of your system.

If you consider the processor as the brain of your machine, the motherboard is the central nervous system, responsible for relaying information between all the internal components. It's the bit that all the other bits plug into. In other words, the motherboard is the electronic glue that pulls together all the parts that make up the PC and presents you with a working machine. While the motherboard itself is unlikely to make your machine operate any more quickly (this will be determined by the speed of your CPU), it is essential to have a stable, reliable unit on which to build the rest of the system.

The motherboard plays home not only to your processor and memory, but also all of your expansion cards, such as your graphics controller, your hard drive and CD-ROM connectors, plus external ports. It houses the BIOS (the basic input/output system), an integral part of the PC that controls the simplest configuration of your machine, and performs the POST (power on self-test) health check when you switch on your machine. It also manages the data flow between the computer's operating system and attached peripheral devices.

Differences between motherboards

Differences between motherboards

All motherboards are not born equal, and you can encounter myriad differences. The most important is the type of processor it supports. In addition, there will be memory module slots; expansion slots (such as PCI, PCIe and AGP) so you can add extras like sound and graphics cards; support for the hard and CD-ROM drives; and, finally, connectors for keyboard, mouse and peripherals. It's also becoming quite common for certain models of board to have some built-in basic sound or graphic capabilities, and even integrated networking capabilities. Some motherboards even have 2 network ports built in!

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The parts - processors

The parts - processors

The processor is the brains of your computer and contains the logic circuitry to perform the instructions of a computer's programs. A processor has three main tasks: it reads data, it manipulates data, and often it writes data to memory.

One of the most important differences between motherboards is that each will only support certain types of processors, for example, a Pentium 4 or an AMD Athlon 64 chip. This is because different chips have connectors that vary physically from one another. Each motherboard has a specific type of CPU socket, and only processors that fit in that socket can be used on that particular motherboard.

This is an important thing to remember, particularly when you're looking to build your own setup or are upgrading your existing system, because the type of processor you buy will impact on which motherboard you choose and vice versa.

Socket formats

Socket formats

Up until a couple of years ago, processors conformed to the same motherboard Pin Grid Array (PGA), called Socket 7. The processor itself was square and encased in a plastic cartridge. On the bottom was an array of pins that connected to parts of the processor and allowed the chipset to control the chip's operation.

Since then, processors have come a long way. Nowadays, there are five types of sockets you will commonly encounter, denoted by the number of pins in the socket:

  • LGA755. Used for nearly all current Intel processors, including the Pentium 4 5xx, 6xx and 8xx ranges, along with the Celeron 3xx range and the Pentium D 8xx and 9xx ranges.
  • Socket 478. Used for older Intel Pentium and Celeron processors. It has become increasingly rare as the older processors are phased out.
  • Socket 754. Used for AMD Sempron and a limited number of AMD Athlon 64 processors. Only the slower Athlon 64s use this and these CPUs do not support dual channel memory configurations.
  • Socket 939. Used for the faster AMD Athlon 64 processors, along with AMD Opteron and Athlon 64 X2s. These CPUs support dual channel memory configurations.
  • Socket A. Used for older AMD Athlon XPs and Duron processors.
It's absolutely vital that you get a motherboard that matches your processor type. If you're buying an Athlon 64, be particularly careful, since this type of processor comes in two different socket types, depending on the speed. For instance, the Athlon 64 3400 fits in a Socket 754, while the Athlon 64 3500 plugs into a Socket 939. The Athlon 64 3200 can be bought in either a Socket 754 or 939 form. Our general recommendation is that, if you plan to buy AMD, get a Socket 939 motherboard and processor, since that gives you headroom for future expansion and more advanced capabilities, such as the ability to implement dual channel memory configurations, which noticeably improves system performance.

Intel processors

Intel processors

Pentium 4 Processor

In 2004 Intel changed its processor number scheme, abandoning the GHz rating in lieu of an abstract model numbering scheme. Now Intel processors are arranged in families, such as the 3xx (Celeron), 5xx (Pentium 4), 6xx (Pentium 4 EM64T) and 8xx (Pentium 4 dual-core) families. Within a given family, the higher the number, the faster the processor; for instance the Pentium 4 660 runs at 3.6GHz, while the Pentium 4 630 runs at 3.0GHz. If you find the new numbering scheme confusing, don't worry - most sellers will be more than happy to tell you the GHz speed of any processor they are selling.

The four main families of Intel desktop consumer processors break down as follows:

  • The Celeron (3xx) processors are entry-level CPUs, designed for low-cost systems. They don't have as much internal memory ("L2 cache") as other Intel CPUs.
  • The Pentium 4 (5xx) processors are the mid-range processors. They are faster, on a clock for clock basis, than Celerons, but lack 64-bit extensions.
  • The Pentium 4 EM64T (6xx) processors have 64-bit extensions, similar to those found in the AMD Athlon 64. They're best used with the new 64-bit version of Windows XP, which can make the most of their extra power.
  • The new Pentium 4 Extreme Edition dual-core (8xx) range as well as the Pentium D (8xx and 9xx) range, essentially have two 6xx processors on a single packaged chip, effectively making the system a dual-processor system (even though it only has "one" CPU). The Pentium 4 dual-core processors require motherboard with a supporting chipset, such as the Intel 945/955X chipsets. The nForce4 SLI chipset also supports dual core CPUs, but it is up to the motherboard manufacturers to implement this feature of the chipset. Double check on the vendor's website to make sure the particular board you are after does support dual core.

All of these current Intel processors fit into LGA755 motherboards, although you will need a supporting chipset if you plan to install an 8xx processor.

AMD processors

AMD processors

In its consumer line of products, AMD has boiled its vast collection of different products down into three core models: the Sempron, the Athlon 64 and the Athlon 64 X2. You may still see the rare Athlon XP around, but we recommend avoiding them.

AMD has an unusual naming schema, basing its product names not on the actual GHz rating of the processor, but on the GHz rating of an Intel processor of equivalent speed. For instance, the Athlon 64 3000 only runs at 2.16GHz, but because it is as fast a 3.0GHz Intel Pentium 4 (because of improved processing efficiency), AMD call it the Athlon 64 3000. This is done to reduce confusion for buyers deciding whether to buy Intel or AMD. And if you're worried that AMD are highballing their comparative speeds, don't be - if anything, the AMD processor speed equivalents are conservative. As an added bonus, the naming schema aligns the AMD processors, making it easier to choose between different types of AMD processors (for instance, it makes it easier to decide whether to buy Sempron or Athlon 64, because both processors are rated on the same scale).

  • The Sempron is AMDs answer to the Intel Celeron. It's a very low cost processor based on the Athlon XP. It lacks 64-bit extensions. It fits in a Socket 754 motherboard.
  • The Athlon 64 is AMDs mainstream and high-end processor. It has 64-bit extensions (which require the new 64-bit version on Windows to make the most of). Some use 754-pin sockets, others 939. Check which you have before buying your motherboard.
  • The Athlon 64 X2 is a dual-core processor, integrating two Athlon 64 CPUs on a single piece of silicon, effectively making it a dual-processor system on a chip. Unlike the Intel dual-core solution, the X2 does not require a special chipset, and should run on any Socket 939 motherboard (although, at the time of writing, the X2 had not been released, so we cannot confirm that every Socket 939 motherboard supports it).

Dual processors and dual-core processors

Dual processors and dual-core processors

Dual processor motherboards are usually only found in server setups and high-end desktop PCs that use the functionality for intense graphics CAD and design work. Therefore, dual processor boards aren't really applicable to the consumer desktop PC market. However, the recent introduction of dual-core processors by both Intel and AMD is bringing multiprocessing to the masses.

A dual processor system is exactly what the name implies - a system with two processors. You need a motherboard with two processor sockets to make this work (and such motherboard tend to be expensive). A dual-core processor is a little different, however. A dual-core processor is a single chip that has multiple processing "cores" on it. It will appear to the operating system as two processors, act the way two processors would act and have the same kinds of advantages as a dual-processor system has. It is only one chip, however, and only requires a single standard socket on the motherboard.

AMD's Athlon 64 X2 (which has the memory controller on the chip), should work in any Socket 939 motherboard. Intel dual-core processors (which leave memory control to the motherboard's chipset) require a supporting motherboard.

By next year, both Intel and AMD expect that the bulk of processors shipped will be dual-core models.

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Pentium chipset

The second way in which motherboards differ is their chipset. The chipset is made up of a series of chips integrated onto the motherboard, which, together, control the system and its capabilities. All components, from the memory to the peripheral devices, communicate with the processor through the chipset. If you think of the motherboard as the physical hardware, the chipset is the logic that underlies it. It is the part that dictates how different components actually talk to one another and is the most important component on the motherboard.

Processor development and chipset design also go hand in hand - so much so that the chipset is built to support the facilities offered by a certain processor. There used to be a number of chipset vendors on the market, but the consumer market has now been pared down to just a few: Intel, AMD, Nvidia, Silicon Integrated Systems (SiS) and VIA Technologies.

Because motherboards are designed around the capabilities of the chipset, users cannot upgrade the computer's chipset without upgrading the motherboard as well. Therefore the chipset and processor you choose will be crucial in deciding what motherboard is best for your system, and vice versa.

The chipset uses the DMA (Direct Memory Access) controller and the bus controller to organise the steady flow of data that it controls.

Alongside the DMA and bus controllers, the chipset's many functions include the memory controller, hard drive controller, PCI, PCIe and AGP bridges, RTC (real time clock), IrDA controller, keyboard controller, the USB interface and mouse controller. The chipset manages the interaction of the various connectors. Nearly all new chipsets have a bunch of extras added in - integral support for sound output, networking and FireWire for instance.

A chipset is usually (but not always) split into two main parts - the north and south bridges. The north bridge takes control of the major functions such as the memory, cache, and AGP connectors (more on these below), while the south bridge controls the non-core functions of the motherboard, such as the PCI bus, integrated audio, EIDE, SATA, serial and USB controllers.

Chipset manufacturers

Chipset manufacturers have produced a large range of chipsets, based on a variety of north bridge and south bridge types. The most recent, and most advanced, releases for Intel processors are the Intel 955X Express Chipset, the Nvidia nForce4, the SiS655 and the Via PT894.

For AMD motherboards, look for recent chipsets including the Nvidia nForce4, the SiS761 and the Via K8T890.

Below, we've included a list of many chipsets you might see appear in motherboards right now.

For Intel processors For AMD processors
AMD None AMD-8151, AMD-8132, AMD-8131, AMD-8111
Intel Intel 955X Express, Intel 925X/XE Express, Intel 915G/GV/GL/PL/P, Intel 875P, Intel 910GL, Intel 865G None
Nvidia nForce4 SLI nForce2, nForce2 Ultra 400, nForce2 Ultra 400GB, nForce2 400R, nForce3, nForce3 Ultra, nForce3 Ultra 250, nForce3 Ultra 250GB, nForce4, nForce4 Ultra, nForce4 Ultra, nForce Professional 2200, nForce Professional 2050
SiS SiS649, SiS656, SiS655TX, SiS655FX, SiS648FX SiS761GX, SiS756, SiS755FX, SiS755, SiS760GX
Via VIA PM800, VIA PT800, VIA PM880, VIA PT880, VIA PT880 Pro, VIA PT894, VIA PT894 Pro VIA K8T890, VIA K8T800, VIA K8T800 Pro, VIA K8M800

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Choosing a chipset

Choosing a chipset

When deciding on the chipset to use in your system, you need to consider several factors. Which processors run with it and how much RAM will it support? Does it support PCIe (PCI Express)? Will it support the parallel ATA (PATA) for your older hard disks?

You also need to find out which functions are handled by the chipset - for example, integrated graphics. This saves money and is good for consumers who are not interested in high-level graphic detail, effects and speed, but is to the detriment of future upgrading if there's no AGP or PCIe slot on the motherboard (more on this later).

Memory support

Memory support

Like processors, memory technology has experienced a period of turbulent design, evolving through many different forms. Up until a few years ago, 72-pin SIMMs (single inline memory modules) were the norm, seen coupled to Pentium processors.

Next came DIMMs (dual inline memory modules), which only require one module to be used at a time, and are compatible with current SDRAM and DDR (double data rate) technology. You can put as many DIMMs in your PC as your motherboard has memory slots. You can mix and match DIMMs, so if your motherboard has two memory slots, you could put one 512MB and one 1GB memory module in, for a total of 1.5GB of memory.

DIMMs come in different flavours -- PC100 and PC133 for SDRAM, and PC2100, PC2700 and PC3200 for DDR SDRAM. The numbers relate to the speed at which they can operate (although the DDR numbers use a different measuring system).

Nearly all memory you buy now will be DDR memory. The most common type of memory available, and the type that nearly all new motherboards support, is PC3200, which runs at 400MHz. You can get 512MB of PC3200 DDR SDRAM for about $70 now.

If you have a new Pentium 4 motherboard, however, the chipset might be able to support the faster DDR2 memory. DDR2 increases the clock rate of the memory, and therefore, the speed at which the computer's processor can withdraw data from the memory. You can get 512MB of 533MHz DDR2 memory for about $110 now. It's more expensive than the 400MHz PC3200 memory, but well worth the extra money.

You may also see some versions of SDRAM advertised as ECC SDRAM. The ECC stands for error checking and correction and basically describes a process of checking data for errors and correcting them "on the fly". For instance, RAID is a form of error correction (see RAID explanation below).

Error correction works on the following principle: when a unit of data is stored in the system's RAM, a code that describes the bit sequence in the unit is created and stored alongside it. When the system goes to retrieve this unit of data, another code is calculated, which is then compared with the original code.

If the codes match, the data is sent. If the codes don't match, the missing or problematic bits are determined through the code comparison and supplied or corrected. The data that is still in storage is left uncorrected, hopefully to be replaced by new data.

If the error continues to occur in the same place after the system has been turned off and on again, the detection technology records the problem as a hardware fault.

ECC SDRAM is used primarily in servers, so it probably won't influence which motherboard you should purchase for your desktop setup. You will also need a chipset, which supports ECC in order to reap the benefits of this technology. ECC memory costs considerably more than regular (non-ECC) memory.

Hard drive support

Hard drive support

The three main types of PC hard drive interfaces on a motherboard are the parallel ATA (Advanced Technology Attachment), also known as the IDE interface, the serial ATA (SATA) and SCSI (small computer system interface).

Most consumer motherboards you buy now will have a mix of parallel ATA (PATA)/IDE ports and SATA ports. Typically, you would use the PATA ports to plug your CD or DVD drives into, while you plug your hard disks into the SATA ports. The important thing is that your motherboard has interfaces that support your devices. Hard disks, for instance, come with either SATA or IDE attachments. You motherboard needs to have the right one for your hard disk (or visa versa).

A very few motherboards support the third connection standard -- SCSI. SCSI is fast and can support more devices, but tends to be more expensive than its counterpart and is difficult to set up.

EIDE/parallel ATA

The EIDE interface evolved from the IDE interface, which supported both CD-ROM and hard drives. This then became UDMA (ultra direct memory access), which evolved from DMA and provided faster maximum data rates. In general, motherboards have one or two UDMA channels. Each channel can support two devices (so if you motherboard has two EIDE ports, it can support up to four EIDE devices).

Up to UDMA33, a 40-pin cable was used for all drive connections. The next advance, UDMA66, required an 80-wire cable but was backwards compatible, in that it also used a 40-pin connector. To obtain a UDMA66 (or faster) connection, the motherboard and all devices you attach must support UDMA66.

Ultra-UDMA is also referred to as Ultra-ATA or EIDE, and typically will be advertised as Ultra ATA33, Ultra ATA66, Ultra ATA100 and Ultra ATA133.

Ultra-ATA 133 is the most common interface today, providing a peak data transfer of 133MBps.

Serial ATA

In addition to the above ATA ports, which are a parallel interface, newer motherboards now feature Serial ATA ports. Serial ATA is a replacement for PATA, being faster, easier to configure and using much less bulky cabling. SATA and PATA are likely to co-exist in motherboards for some time, however, as the older PATA is phased out.

SATA hard drives work with current operating systems and are software compatible with parallel ATA. Adapters can be used to plug parallel ATA drives into SATA ports, but these are not a sure thing and not all adapters work with all chipsets.

A Serial ATA cable The biggest benefit of SATA is its increased data transfer rates. While the fastest performing parallel ATA drives offer data transfer speeds of 133MBps, SATA operates with a data transfer speed of 150MBps. SATA drives also take up less room within the PC case due to smaller cabling (making them great for use within compact systems), and are more effective than parallel drives for cooling.

You will find at least two Serial ATA ports on the latest motherboards, with most boards boasting four or more ports. Unlike PATA, SATA works on a one-port, one-drive basis, so you don't need to "daisy chain" drives as you do with PATA. With SATA, drives can be arranged in RAID configurations for up to two drives.

If the motherboard you are looking to purchase is enabled for SATA, it will be noted on the board packaging with the SATA working group's official logo, or in the motherboard manual.

If you're really a bleeding edger, you can look for motherboards that support the new SATA2 standard, which is technically capable of speeds twice that of SATA. With current drives, however, the speed of the interface is not the limiting factor (150MBps is more than enough to support the peak speed of any available hard drive), so the benefits of SATA2 will not be seen for some time. One major benefit of SATA2 is a feature called NCQ (native command queuing). This feature organizes the flow of data from the motherboard chipset to the hard drive controller in such a way that the hard drive does not have to stress itself too much when retrieving your data.

For example, if a set of data requests are sent at different times that are located near the centre of the hard drive, but there are also some requests within that group of data that are located on the outer edge of the disk, then the data requests will be organized so that all the requests for data near the centre of the drive are performed together and then the ones at the outer edge are performed together. This improves seek times as it cuts the amount of travel the hard drive heads have to go through. To benefit from NCQ, your hard drives need to support the SATA2 interface and so does your chipset.


Pronounced "scuzzy", this interface allows users to connect up to 15 devices (depending on bus width) on a single SCSI port in a "daisy-chain" fashion. SCSI was originally developed by Apple and is supported by most operating systems.

SCSI has also been through a variety of evolution stages, from the original SCSI, now known as "plain" SCSI-1, right through to the latest Ultra-320 standard, capable of 320MBps transfer rates.

However, the increased performance and functionality of SCSI does come at a price: motherboards that feature dedicated SCSI ports are at the higher end of the spectrum, and are usually designed for servers.

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Peripheral devices

Peripheral devices


A Universal Serial Bus (USB) is a bus standard for connecting peripherals to your PC.

Up until fairly recently, motherboards were based on the original USB 1.1 standard. This offers users data transfer rates of 12Mbps and is used to connect low to middle bandwidth devices such as scanners, printers, keyboards and mice to a PC. A single USB port can be used to connect up to 127 peripherals. The USB standard also supports plug-and-play installations and hot plugging (plug-and-play is the ability to add and remove devices to a computer while the computer is running and have the operating system automatically recognise the change).

USB 1.1 has been now superseded by the backwards-compatible USB 2.0 (also referred to as "hi-speed USB"), which can offer data speeds of up to 480Mbps - 40 times that of its predecessor. USB 2.0 supports higher-bandwidth devices, such as cameras, next-generation scanners, video conference cameras and fast storage units. USB 2.0 should look the same as 1.1 from a user's point of view, with the only noticeable difference being faster data transfer from peripherals.

A motherboard will generally have four to eight USB ports, one serial port and one parallel port. Again, motherboard manufacturers can build different numbers of USB ports onto the board.


IEEE-1394, otherwise known as FireWire or i.Link, is a serial bus designed to connect devices to your computer -- similar, in practice, to USB 2.0. This peer-to-peer interface allows you to connect up to 63 devices to one another, without the need for a PC and is particularly suitable for high-performance applications and for connecting high-end consumer devices such as an external DVD burner, or a digital video camera.

Most new motherboard now come with between 1 to 3 FireWire ports, which can be used by connecting a special D-bracket, which is usually supplied with the motherboard, to an internal pin header on the motherboard. Some budget motherboards do not have FireWire at all though, so make sure you check beforehand if this is going to be a feature you require.

The original FireWire standard offered data transfer speeds of up to 400Mbps. A new version of FireWire, called FireWire 800, offers data transfer speeds of 800Mbps, making it twice as fast as the existing FireWire 400. The new standard, which was released in early 2003, is backwards compatible with the older version so you can still connect FireWire 800 devices to existing 400 ports, although they will only run at the slower speed.

Several industry players are now referring to the older 400Mbps FireWire as "FireWire A" or "1394a", and the new 800Mbps standard as "FireWire B" or "1394b", so you may see FireWire-based devices described using these terms. At this stage however, only some flagship model motherboards have the newer FireWire standard.

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Expansion slots

Expansion Slots

One of the most attractive things about PCs is their upgradeability. To add extra functionality to your machine, you simply need to drop in a suitable card.

There have been a number of different expansion slot interfaces built into the motherboard for expansion cards such as sound cards, graphic cards, modems and network cards. There are four main types of expansion slots you'll find in a new motherboard - the now very rare ISA slot, the PCI slot, the AGP slot and the PCIe slot (PCIe slots are, incidentally further broken down into various speeds).

A given motherboard is going to have a certain number of expansion slots of each type it supports. The specifications may tell you, for instance, that the motherboard has three PCI slots, two 1X PCIe slot and one 16X PCIe slot.

The key question you'll be asking is whether to get a PCIe or AGP motherboard. The two are (not technically, but in practice) mutually exclusive. PCIe is newer, faster and more flexible, but if you have an AGP graphics card that you really want to use, you will need to buy an AGP motherboard.


Originally developed by Intel, the Peripheral Component Interconnect (PCI) is a local bus channel used to transfer data to (input) and from (output) a computer and to or from a peripheral device. Most PCs have a PCI bus that is usually implemented at 32-bits and provides a 33MHz clock speed with a throughput rate of 133MBps, although you can get PCIs that transmit 64-bits in an expanded implementation.

PCI cards come in two lengths. The full-size PCI is 312mm long, and short PCIs range from 119mm to 167mm. Most current PCI cards are half-sized or smaller.

Nearly all motherboards, even PCIe motherboards, feature PCI slots, since most add-in cards still use the PCI standard. Usually the minimum is three, but motherboard manufacturers have extended this up to as many as six slots. This is important, because if you want to use a lot of expansion cards, you will need as many PCI slots as you can get.

Accelerated Graphics Port (AGP)

In addition to PCI slots, many motherboards will also feature an accelerated graphics port (AGP) slot. The AGP slot is exclusively for graphics cards. It is being phased out with the introduction of PCIe.

The AGP bus is a dedicated high-speed port just for the graphics controller. It offers superior bandwidth capacity to the PCI bus, meaning data can be transferred in bulk and at a faster speed. This is because graphics operations using an AGP slot do not have to share bus bandwidth with other peripherals, like they would using the PCI bus. It also means the PCI bus can run more quickly, as it is free to serve other devices, such as the hard disk, sound card, modem and network cards.

All new AGP ports will be '8X', which means that they run eight times as fast as the original AGP ports (you need an 8X AGP port to run an 8X AGP card). An 8X AGP port runs at roughly the same speed as an 8X PCIe port.

PCI Express

A new and increasingly common standard, PCI Express (PCIe) was designed to replace both AGP and PCI. In the next few iterations of motherboard technology, we can expect to see both AGP and PCI totally phased out in lieu of PCIe. For the time being, however, many PCIe systems still have legacy PCI slots, for compatibility with the vast array of PCI expansion cards on the market.

PCIe slots come in a variety of different speeds - 1X, 2X, 4X, 8X, 16X and 32X (roughly corresponding to the AGP speed levels). A motherboard may have two 1X slots and one 16X slot, for instance. The slots for different speeds are physically different - the 1X slots are quite short - barely an inch, while successive levels get progressively longer.

One of the more interesting design aspects of PCIe is that you can use cards that are smaller than the slots. You can put a 4X card in a 16X slot, for instance, or a 1X card in a 4X slot. It won't fill the slot to the end, but it should work just fine.

In a typical motherboard configuration, the longest slot (usually 16X, but sometimes 8X) is there to be used for the graphics card. Most PCIe graphics cards you buy will be of the 16X variety. The shorter 1X and 4X slots are there for less-bandwidth intensive devices like sound cards and TV tuner cards.

One some motherboards, you may find more than one long (16x) slot. That's because the motherboard has been designed with SLI (scalable link interface) configurations in mind. With some graphics cards, most notably Nvidia graphics cards, you can actually put two graphics cards in the one system and they will work together to render a scene, each taking half the screen. To do this, you need two slots capable of supporting the graphics cards. In practice, that means having a motherboard with two 16X PCIe slots. SLI is not possible with AGP, which is limited to one slot per system.


The predecessor to PCI was the Industry Standard Architecture (ISA), a standard bus architecture. ISA allows 16-bits at a time to flow between the motherboard circuitry and an expansion slot card and its associated devices.

ISA and PCI were easily distinguishable: ISA slots were black, and PCI white. If you have a look inside a modern PC, however, you won't find any black ISA slots, as the standard has been phased out.

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Integrated interfaces

Integrated interfaces

Increasingly, chipset manufacturers are incorporating graphics, sound and networking controllers into the board itself, obviating the need for add-in cards. These can be beneficial depending on the use you make of your system, for instance, the level of support offered may not be enough for the types of applications you want to run on your system. Therefore, it's important to look at which features have been integrated into the chipset and motherboard before you make your purchase.

Integrated graphics

After a spurt of popularity, integrated graphics support on the motherboard has become increasingly rare. It obviates the need for a separate graphics card but doesn't always offer the highest quality in 3D games performance. If you are planning to use your setup for office applications only, an on-board graphics chip should suffice. The 3D support of integrated graphics chips, however, tends to lag way behind that of dedicated cards, so diehard gamers will probably find the built-in support inadequate, and should consider installing a dedicated card.

Intel's 915G chipset for instance, offers Intel's integrated Graphics Media Accelerator 900, which supports both 2D and 3D graphics and uses a chunk of the computer's main memory for graphics processing. Other chipset manufacturers such as VIA Technologies and SiS also offer 2D/3D graphics engines built into the chipset with similar capabilities.

In many cases, motherboards with integrated graphics will still have an appropriate AGP or PCIe slot to insert a graphics card. If you opt to use this slot, then the inserted graphics card will "override" the motherboard's integrated graphics.

Sound Support

The story of integrated sound support is a little different. Nearly every new motherboard you will buy today has some form of integrated sound processing capabilities, sparing you the need to go out and buy a separate sound card.

The on-board sound in recent motherboards has actually become quite sophisticated, in some cases rivaling card-based solutions and offering six or even eight-channel sound.

A motherboard with integrated sound will have speaker, line and microphone sockets on its backplate, accessible to the exterior of the PC.

Some boards also ship with proprietary utilities that allow you to tune into FM radio and play music CDs without having to load up the operating system.

It is important to note though, that onboard sound uses your systems CPU to process sound. This means performance during gaming or other intensive applications could be compromised as the CPU processes this sound. A separate sound card, such as a Creative Audigy2, is well recommended if you are a multimedia and gaming enthusiast as the sound card will take the sound processing load off the system's CPU and do all the processing onboard. Likewise, most integrated sound chips have a much lower signal to noise ratio than most current sound cards. Signal to noise ratio is basically the amount of signal that can be heard relative background noise and is measured in decibels. A higher number is better.

On-board networking

Another interface which has become more common on motherboards over the past 12 months is the on-board LAN (Local Area Network) controller. Almost all new motherboard come with 10/100 or even Gigabit network controllers these days, and some high-end motherboards even come with 2 Gigabit ports!

On-board LAN can come in a variety of types, but the most common on desktop boards is integrated 10/100Mbps Ethernet (Fast Ethernet). This is the most widely installed type of LAN.

"10/100Mbps" refers to the speed at which the PC can retrieve data from the network. 10/100 is a switchable network interface that can be used with either of the two most commonly installed Ethernet systems: 10BASE-T or 100BASE-T. Most new motherboards also now support Gigabit Ethernet (1000BASE-T) networking natively. Gigabit Ethernet is backwards compatible with Fast Ethernet, so Gigabit motherboards can connect to Fast Ethernet networks.

Some new motherboards are also coming with wireless ("Wi-Fi") networking built in, most commonly 802.11g. Wireless networking allows you to communicate with other local PCs through a wireless access point or wireless router. 802.11g supports communications at a theoretical 54Mbps (some implementations even support up to 108Mbps in "turbo" mode, using the 802.11g protocol). If you plan on using wireless networking, integrated Wi-Fi can save you $70 or more on an expansion card.

On-board Bluetooth support

As well as providing on-board support for LANs, motherboard manufacturers are also delving into personal area networks (PAN) via on-board Bluetooth technology. Bluetooth can be used for wireless control of peripheral devices like printers, handheld PCs and mobile phones.

MSI 845E Max2 motherboard

Integrated Bluetooth solutions can be used for either Point to Point or Point to Multi-Point Wireless transmissions between the PC and the Bluetooth devices within a 100m range.

Optional interfaces

A wide array of new interfaces are popping up on motherboards as optional extras, which concentrate on specialised peripherals coming into the market.

For example, a selection of motherboards offer on-board Memory Stick, Smart Card, CompactFlash and Secure Digital card interfaces as extras. These are basically dedicated socket points (also known as pin headers) for you to connect your smart card reader or SD card reader to your PC. Motherboards with these interfaces do not usually come bundled with cable connectors, however, so if you are planning to connect through any of these technologies to the motherboard you will need to invest in the cables separately.

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Motherboard form factors

Motherboard form factors

As we told you at the start of this guide, motherboards come in different shapes and sizes. However, to ease the process of designing cases, certain formats, known as form factors, have been standardised.

The form factor refers to the physical layout of the motherboard. It is used to determine the board's feature design, including the physical size and shape of the motherboard, the location of mounting holes and slots, and power supply connectors. You need to match your motherboard form factor with a computer case that supports the particular form factor.

Today, the most common form factor is ATX. The ATX specification not only dictates where the connectors on the back of the motherboard should be (to line up with the holes in the case), but also encompasses details such as the power supply connector. Power supplies are currently available in ATX +12V form factors (20-pins) for most motherboards, but ATX +12V Version 2.01 power supplies are also available for some motherboards (for example, those based on Intel's 925X chipset) that have 24-pin power connectors as well as power connectors for SATA drives and high-end PCI Express graphics cards (such as the Nvidia GeForce 6800 ultra). There are variations on form factors - for example, MicroATX and Mini ATX take the basic ATX specification, but have fewer expansion slots to allow for smaller cases (they can, if desired, still go into larger ATX cases, however).

Prior to ATX, AT was the de facto standard, while NLX was used to create slimline PCs. The biggest difference between the ATX and AT form factors is the power supply mounting configuration. The ATX power supply blows air through the case and across the processor, while the AT form blows air out of the case. The ATX form factor also holds more integrated I/O (Input/Output) and includes a PS2/mouse connector.

Briefly, I/O describes any program, operation or device that transfers data between the devices and a computer. Devices can be divided into those that are input-only, such as keyboards and mouses, and output-only, like printers. The transfer of data to and from the processor to the memory or expansions slots is also referred to as I/O.

AT has been phased out, so you won't find any motherboards based on this form factor on retailers' shelves.

In the future we're likely to see more of a new type of form factor - the BTX (balanced technology extended) form. BTX is designed for better airflow around the components that need it, and to allow PC designers to bring to market more interesting PC designs. BTX is designed to be scalable, from smaller than MicroATX to larger than ATX, in order to support variable numbers of expansion slots.

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The functions - BIOS and POST

The functions - BIOS and POST

As we mentioned earlier, the motherboard also houses the BIOS (the basic input/output system). An integral part of the PC, the BIOS controls the simplest configuration of your machine, and performs the POST (power on self-test) health check. This determines whether the computer's various components, such as the keyboard, memory, disk drives, and other hardware, are functioning properly.

If all the necessary hardware is detected and found to be running smoothly, the computer will start up. If, however, the hardware is not detected or is malfunctioning, the BIOS issues an error message, which may take the form of text on the display screen and/or a series of coded beeps, depending on the nature of the problem. These warning beeps or alerts will vary from board to board, depending on which type of BIOS is installed.

Some motherboard manufacturers for example, have introduced voice warnings into their POST reporters, while others will display error messages on-screen.


A recent innovation to BIOS is DualBIOS technology. The purpose behind DualBIOS is to provide a backup to the primary BIOS. If the main BIOS chip fails, for whatever reason, the second BIOS chip automatically takes charge of the system and keeps it running.

For instance, if the BIOS data has become corrupted but the chip is still functioning electronically, the DualBIOS utility will issue a series of automatically activated features via the second BIOS chip, which allow you to restore the primary BIOS to health. This is particularly useful against viruses targeted at disabling your BIOS.

If the primary BIOS chip has an electronic fault, the second chip simply takes its place.

DualBIOS makes this possible through its built-in one-way flash utility, which can flash your system's BIOS from backup to main and vice versa. Because the second BIOS chip is your computer's BIOS backup, all of the good information will have been stored automatically.


Another controller you may find on-board is RAID, which is short for Redundant Array of Independent Disks and basically refers to various methods used to store or span data across multiple hard disks.

The basic principle behind RAID is to combine multiple drives into what the operating systems will recognise as a single drive, improving performance, capacity and reliability of transferring data.

RAID achieves this by establishing multiple drives into an array of drives, which can be read and written to in parallel. This allows the system to retrieve large amounts of data from several sources at the same time. Retrieving several sections of data simultaneously increases the speed with which the data is transferred.

Six different types of RAID are available, ranging from the basic RAID 0 to RAID 5. They vary in the level of redundancy, data storage techniques and multiple drives they support.

RAID 0 employs the technique of striping, in which data is divided into a variety of units, ranging in size from 512 bytes up to sectors of several megabytes. These "stripes" are then interleaved around the drives, so that data is situated across multiple drives.

RAID 0 doesn't really fit with the concept of RAID as it offers no redundancy of data, i.e., if any of the drives in the chain fail, all data is lost. By using the striping technique, RAID 0 can improve the performance of the system and increase the speed with which data is transferred. This is great for applications that need very high-speed storage, such as image or photo programs.

RAID 1 does not use striping techniques but, instead, uses disc mirroring to improve the performance of your PC. Much like manually backing up your data from your hard drive to a storage disc, RAID 1 allows you to make a copy of data on one drive on another - in other words, mirroring the two drives. This can be beneficial, because if one drive fails, a complete copy of all your data is accessible on the other. This is known as fault tolerance. This mirroring process can also hasten the reading of information from your drives, as both drives can be read at once. It does, however, halve your storage capacity.

Higher levels of RAID, such as RAID 3, 4 or 5, also use parity techniques, which involve checking whether data has been lost or written over when moved from one place in storage to another or when transmitted between computers. Some RAID versions will store parity information on one dedicated drive, and others will rotate the information across all of the drives.

A range of motherboards on the market today offers built-in RAID controllers for desktop PCs, but they will generally only offer RAID 0 or RAID 1 support. Some will also support JBODS (just a bunch of disks), which unifies an arbitrary set of disks into a single logical "drive"; and RAID 0+1, which combines striping with mirroring. You won't find many motherboards in this space that come with built-in support for higher levels of RAID.

However, if you buy a board without RAID support but are keen on using RAID, hardware RAID controllers will communicate with the system and hard drives through either the SCSI or IDE/ATA interface. The more complicated and high-end RAID types, such as 3 or 4, are usually based on SCSI, so if you want to use these types of RAID, you will need to purchase a motherboard with a SCSI interface (again, a more expensive choice).

Hardware RAID is divided into internal and external RAID controllers. The internal RAID controllers are usually controller cards that are installed in the bus system of the computer - and look much like a SCSI or IDE adapter.

External RAID puts the controller into a case of its own. These are more often seen in high-end servers, which will employ a separate enclosure to house both the RAID controller and the hard drives. The interface used for external RAID is commonly SCSI.

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Considerations when choosing the motherboard for you

When you're choosing a motherboard, you're also choosing which type of processor, chipset and memory you will be able to use. Although most chipsets can support more than one type of memory, most motherboards will only allow you to choose one.

There are also general considerations besides performance to keep in mind when evaluating motherboards. Since motherboards by different manufacturers with the same chipset will usually have similar performance in terms of speed, other factors have been emphasised. Reliability and special features, for instance, are more important overall than a couple of percentage points' difference in speed.

Not all the important things about motherboards are electronic - as the central connection for all the computer's components, a motherboard needs to be physically sound. Although boards are made to an official size standard, they're not all identical. Small variations in case shapes and in the placement of sockets can occasionally mean that it's difficult to fit some motherboards into some cases, or to add expansion cards. Alongside the physical size of the motherboard, it is also important to ensure the board has enough expansion slots to accommodate all of your network, sound and graphics cards.

If you're upgrading an older computer, the case may not support some motherboards. Remember, older AT-style cases won't fit the ATX-type motherboards currently in use. Even newer ATX cases may need to have the power supply upgraded to cope with the requirements of the latest processors. The latest Pentium 4 boards require supplementary 12V power connectors that are only available on ATX +12V power supplies.

What to ask yourself

Before investing in a motherboard, ask yourself which tasks you intend to perform with your system. If, for instance, you plan on using your setup primarily for office applications and do not need 3D graphics, then a basic motherboard with integrated sounds or graphics will most likely suffice. On the other hand, if you're into games and plan on using the system to test run the latest software on the market, then a board with extra expansion slots for graphics and sound cards or one that is easily upgradeable would be more suitable.

Of course, the kinds of additional features that can be found on the motherboard, such as additional expansion or memory slots or RAID functionality, will cost you. In addition to what you consider to be your needs, you must also decide how much money you want to spend.

Questions to ask the retailer

Questions to ask the retailer:

How much is the motherboard?

Motherboards can vary in price, with the majority of desktop models ranging between $120 and $400. Basic dual and multi-processor boards start at around $400.

The cost of a motherboard is not quite as relevant as the cost of the total package. You may, for example, buy the cheapest board on the market, but find that the type of RAM it supports is more expensive than the next board up. Or, you may opt for a motherboard with integrated graphic and sound support, but realise when you're playing the latest Quake game that you need a higher level of both.

The best thing to remember is to compare the costs with the features you are receiving and take into account all of the components you need to buy before selecting the board.

What sort of warranty do I get with this?

Warranties generally last for 12 months, for both Intel and AMD platforms.

Is this a validated board?

Both AMD and Intel maintain certification levels for motherboards, and test and evaluate motherboard products from a variety of manufacturers. This is particularly useful for buyers, as it will mean the board has been tested and approved to work with the processors and chipsets it has specified and is thus clear of bugs, 'quirks' or related problems.

Both companies advise that when you are investing in a board you should check whether it has been validated. It could save you unnecessary problems later.

Should I check its RAM compatibility?

Not all motherboards and memory modules are compatible. Prior to purchasing memory for your motherboard, check out the motherboard vendor's web site to see if it has a list of memory modules that are compatible with its boards.


Check out PC World Magazine for regular reviews and performance tests of the latest motherboards on the market.

This guide was last updated in March 2006.