ATXfamily

ATXfamily is a term used to describe the group of motherboard form factors derived from the original ATX standard, established by Intel in 1995 to standardize desktop motherboard size, mounting points, and power delivery. The ATX family covers several sizes that share common characteristics, including standardized mounting hole layouts and compatible power connectors, enabling interoperability among cases, power supplies, and motherboards.

The core members are ATX, MicroATX, and Extended ATX (EATX). The standard ATX board measures about 12 by 9.6 inches (305 by 244 mm). MicroATX boards are 9.6 by 9.6 inches (244 by 244 mm) and fit in many smaller cases. Extended ATX boards increase the footprint to accommodate more expansion slots and features, typically up to 12 by 13 inches (305 by 330 mm). The term FlexATX and other regional variants were used in the late 1990s to describe smaller or differently shaped boards, though they are not as common today.

Power delivery in the ATX family has evolved from a 20-pin main power connector to a 24-pin connector, with additional 4-pin or 8-pin CPU power connectors in modern designs. System builders must ensure the case size, motherboard form factor, and power supply are compatible; not all cases support EATX, and some mini-towers only accommodate ATX or MicroATX.

Today, the ATX family remains the dominant desktop motherboard standard, while smaller form factors like ITX offer alternative options for compact builds.