ATX and mATX are by far the most popular motherboard sizes for desktop computers, and as seen in the list above, are also some of the largest. More real estate on a motherboard allows for greater expansion possibilities and extra features, which make the use of these boards more flexible. A Mini-ITX board may feature just one slot for memory and one slot for an expansion card, while a typical ATX board may feature 4 memory slots and six slots for expansion cards.

Each form factor has its own niche that it fits into, from workstations and gaming systems for larger boards to media centers and in-car computers for smaller boards. There is definitely overlap between the potential applications of each form factor, and other features and capabilities will also influence the targeted use.

2. CPU Socket

The major processor manufacturers, AMD and Intel, are constantly waging a battle to offer the fastest, most powerful processors available. Getting more speed and performance out of a relatively small chip generally requires a change to the physical dimensions as each new generation of processor is released. Therefore, motherboards need to evolve at the same pace in order to accept the new CPUs.

Back in the day, AMD and Intel processors shared a common CPU socket, but those days were short lived. AMD and Intel have since been traveling down their own, relatively parallel, paths of performance and speed increases, while using different designs. Selecting a motherboard for a modern AMD processor eliminates the use of any Intel processor, and vice versa.

AMD's current offering for desktop processors includes the Athlon 64, which is available in Socket 939 and Socket 754 formats. The number in the names represents the number of pins present on the backside of the CPU that connect to the motherboard's socket. The Socket 939 Athlon 64 therefore has a staggering array of nine hundred and thirty nine tiny pins to match up with the motherboard's socket. The Chaintech VNF4 Ultra is an example of a Socket 939 motherboard based on Nvidia's NForce4 Ultra chipset technology. In addition to these two sockets, many AMD processors, including Athlon XPs, Semprons, and Durons, share the Socket A format, also known as Socket 462 thanks to it having 462 pins for connecting to a motherboard.Socket adapters

Intel's latest offering for their Pentium 4 and Celeron processors, LGA 775, doesn't have pins at all and basically swaps the pins to the motherboard for the socket. Perhaps this design move puts the burden of bent pin warranty claims on someone else, but it is fairly unique. The Biostar P4M80-M7 is an example of an LGA 775 motherboard based on the VIA P4M800 chipset. Other Intel processors still on the market utilize the Socket 478 format for Pentium 4 and Celeron processors.

Although most motherboards support just one CPU socket, some applications benefit from having more than one processor to tackle the tasks at hand. Servers and high end workstations are two examples where a dual processor system, such as could be run on the Tyan Thunder i7500 motherboard, might make light work of more advanced applications.

3. Components

'Components' is a fairly vague term to describe this section, but the items to be covered are fairly diverse. Computer systems all use memory, storage devices, and power supplies, but among the many differences motherboards have is the type and quantity of connections for these components.

Most modern systems use DDR memory, but DDR-2 memory is becoming more common and will eventually become the standard. Although some boards provide slots for both types of memory, it is generally the case that either one or the other technology is supported. Besides operating differently, the physical difference of DDR having 184 pins and DDR-2 having 240 pins prevents them from being interchangeable. Going forward, users will have to decide whether they want to jump on the new technology bandwagon when selecting a motherboard, or to try to continue using their existing DDR for as long as possible. Regardless of technology, most motherboards come with 2 to 4 slots for memory, although as mentioned, Mini-ITX boards may just offer 1 slot.

Hard drive technology is changing too, as mentioned in the Tech Tip comparing SATA to ATA hard drives. Most motherboards over the past few years have offered two ATA connections, which could support up to 4 drives. With SATA becoming more popular, some boards now offer a mix of ATA and SATA connections, while others have abandoned ATA all together, and instead offer multiple SATA connections which only support one drive each. In addition to type and quantity, motherboards can also offer choices in hard drive capabilities by integrating RAID controllers onboard, as found on the ASUS K8V SE Deluxe.

As systems become more advanced, they many times impose special power requirements to keep them running smoothly. Most motherboards feature the typical 20 pin ATX power connector, while some server boards may have a 24 pin connection in its place. Motherboards for AMD Athlon 64 and Pentium 4 processors will have a second power connection located in close proximity to the CPU socket for providing the extra power that today's high end processors demand. This special 4 pin connection isn't found on every AMD Socket A motherboard, but it will most definitely be located on an AMD Socket 939 motherboard. Power supplies have been including this special connection for years, but for those upgrading an old system with a new motherboard, the power supply may be just one more item that has to be upgraded as well.