Common motherboard types include ATX, mATX and mITX.
Most modern motherboards are based off the Advanced Technology Extended (ATX) specification released by Intel in 1995. Previously, Advanced Technology (AT) motherboards assumed that large expansion cards could hang over the processor with little clearance, because early processors did not use heat sinks. A push to standardize motherboards brought about the ATX standard, on which the mini ATX standard is also based. Newer mini ITX motherboards were developed to fit into tiny home theater PC (HTPC) computers.
ATX
After 1995, ATX motherboards replaced the earlier Advanced Technology (AT) and Baby AT motherboards. Considered a "full-sized" motherboard, the ATX standard is 30.5-by-24.4 cm and fits into most "full tower" and "mid-tower" sized computer cases. American Micro Devices (AMD) also adopted ATX standards. Consumers can buy ATX motherboards for building either Intel or AMD systems. As of August 2010, most modern personal computers (PC) used some variation of the ATX standard.
Mini ATX
Smaller than the ATX standard, mini ATX motherboards measure 28.4-by-20.8 cm. The name often is shortened to "mATX." To fit in a smaller size, mini ATX motherboards offer fewer memory sockets and less card expansion slots. A typical mini ATX motherboard, for example, only allows for installation of two memory sticks. Due to these limitations, a more powerful machine can be built with an ATX rather than a mini ATX boar. However, mini ATX allows for a smaller computer size. This standard fits in "mid-tower," "micro tower" and "micro desktop" cases.
Mini ITX
Hailed as the smallest and most energy-efficient of motherboard standards, the mini ITX began gaining in popularity after the home theater PC emerged. Some mini ITX boards use low-power, single-core Intel Atom or similar processors; others are compatible with the newest high-end Intel and AMD processors. A mini ITX (mITX) board uses a 17-by-17 mm size and only needs a 100-watt power supply. Like the mATX motherboards, mITX sacrifices power for size by offering only limited upgrade options. These motherboards include built-in graphics and offer one or two card expansion slots at most. No ITX motherboard standard exists, except for one developed in research.
Tags: Advanced Technology, mini motherboards, card expansion, card expansion slots, expansion slots, home theater