What is an ITX form factor motherboard?

ITX motherboards (also known as mini-ITX) are small PC motherboards (17cm by 17cm) that are typically self-contained like their larger ATX counterparts. How self-contained? Try to envision the inclusion of memory sockets, processor, VGA card, IDE bus, floppy port, 10/100 base-T ethernet controller, sound card, firewire (IEEE 1394) and USB ports. Some, but not all, also have Disk-on-Chip (M-system) connectors for solid state storage. Some even have optional RS-422/485 abilities.

Mini-ITX motherboards typically come with a 500MHz to 2GHz low power processor. Some come with processors that do not require fan cooling at room temperature, others require a small (small) fan to keep the processor cool enough. Some case manufacturer make aluminum cases with enough heat sinking so that even the faster processors can run without fan cooling (Nehemiah Hush Silent Mini-ITX PCs).

Computers built from Mini-ITX motherboards are typically not as fast as a regular desktop or notebook computer. However, they still pack quite a bit of processing power due to internal FPUs and 32-bit architectures. Most mini-ITX motherboard use regular DIMMs as their full-size ATX counterparts, which makes memory very inexpensive.