A recent Tech Tip covered the basics of selecting a computer case and made
mention of the various sizes that correspond to motherboards of different form
factors. A few people wrote in expressing interest in understanding more about
the basics of motherboards, and that's exactly what this Tech Tip intends to address.
A motherboard, also known as a main board, is the primary circuit board inside
of a computer, and is where the central processing unit (CPU), memory, expansion
slots, drives, and other peripheral devices are connected. The circuitry on a
motherboard facilitates the communication between all of the devices in the
computer, making them as critical to a system's performance as items such as the
CPU or memory.
The core circuitry of a motherboard is referred to as its chipset, and generally
the manufacturer of the motherboard is not the manufacturer of the chipset.
Intel does produce motherboards with their own chipsets, but buying a motherboard
brand such as Gigabyte, Biostar, and ASUS means getting a board with either a VIA,
Nvidia, SIS, or Intel brand chipset.
1. Form Factor
The different basic shapes and sizes of motherboards are categorized as form
factors. There are several standard form factors available, but some of the more
common ones found in desktop computers include:
The basic sizes of each are as follows:
- ATX: 12" x 9.6" (305mm x 244mm)
- Micro ATX: 9.6" x 9.6" (244mm x 244mm)
- FlexATX: 9.0" x 7.5" (229mm x 191mm)
- Mini ITX: 6.7" x 6.7" (170mm x 170mm)
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