Build A PC

A custom PC configuration guide. © 2000,2001,2002 by Jef Poskanzer.

Motherboard Form Factors

Motherboards come in a few different physical sizes. This isn't a real big issue - just check the form factor on the motherboard you select, and choose a case that fits it.

12" x 13.8". Based on the original IBM PC-AT's board. Obsolete.

Baby AT, a smaller version of the AT board. Obsolete.

305 x 244 mm. Stands for AT-extended - an enhanced version of the AT board. This is the most common form in use today.

244 x 244 mm. A smaller version of ATX. There are some nice small micro-tower cases that take microATX motherboards. If physical size is an issue, look at these.

Flex ATX
229 x 191 mm. Even smaller than microATX.

170 x 170 mm. Even smaller than Flex-ATX! These boards are tiny. Lots of info here.

A workstation/server version of ATX, with some more room. Not common, yet.

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