Overview of motherboards

All motherboards contain similar essential components including processor slots, expansion buses, RAM banks, integrated controllers (either IDE or SCSI), power connectors, and peripheral connectors. It is these essential components that work together to provide the connectivity and communication within the computer.


Although all motherboards have similar components they are based on different form factors and when it comes to motherboards, you need to be familiar with these form factors. Form factors determine the specifications of a motherboard such as its size, shape, physical layout, and so on. When purchasing a new computer system, the form factor is important because you need to ensure that the motherboard fits with the case and other components.

Integrated vs. non-integrated

Motherboards are classified as either integrated or non-integrated. Integrated motherboards contain built-in components that are normally on found by adding expansion cards. For example, a motherboard might have video and network capabilities built right into the board, so you don't have to purchase a separate video card and network card. The obvious downside to this is that if the video or network component ceases to function, you will either have to replace the entire motherboard or disable the malfunctioning onboard component can damage other components on the motherboard, necessitating the replacement of the motherboard.

With non-integrated motherboards, the initial cost is higher because more individual components need to be purchased. In case of component failure, however, replacement of the entire motherboard can be avoided. Another issue that arises with non-integrated motherboards is the availability of expansion slots to support the multiple components.

In server motherboards, it is common to find integrated components such as SCSI and RAID controllers in addition to the video and network cards already mentioned. With large amounts of RAM installed in servers, combined with the fact that there is no need for enhanced video, servers often contain some integrated components. Component failure resulting in a smoked motherboard is still an issue though. To support these components, a non-integrated motherboard would require a minimum of four expansion slots, and this is the main reason components such as video and sound are integrated into the motherboard of a server.

Many motherboard manufacturers offer both types of motherboards. The specific components used in integrated motherboards vary between manufacturers, but they commonly include on-board video, audio, modem, and network adapter card. Some manufacturers will integrate all of these components; others will provide a selection.

Form factors

As mentioned earlier, motherboards are classified by form factors. Form factors essentially define the layout of the actual motherboard including the dimensions, component positioning, mounting holes, number of expansion slots, and so on. There are several different types of form factors including:

• AT/Baby AT

• ATX

• LPX

• BTX

• NLX

The following sections will outline some of the characteristics of each of the form factors listed above, starting with the AT/Baby AT.

AT/Baby AT

The Advanced Technology (AT) was the original IBM form factor design, on which the processor, memory and expansion slots were all arranged in a straight line as shown in Figure A.