ATXStandard

ATXStandard refers to the ATX form factor specification used for desktop PC motherboards and power supplies. Issued by Intel in 1995, it introduced a common motherboard size, a fixed mounting scheme, a standardized rear I/O panel, and a unified power connector to improve interoperability and ease of upgrade. The original ATX layout specified a motherboard measuring 305 by 244 millimeters and a corresponding case geometry to match.

Over time the ATX family expanded to accommodate different needs. MicroATX retains the same basic mounting and I/O practices but uses a smaller board (about 244 by 244 mm), allowing more compact systems. Extended ATX (E-ATX) increases dimensions to support additional PCIe slots and memory, requiring larger cases. The power delivery portion evolved with ATX12V and EPS12V extensions, resulting in a system that commonly uses a 24-pin main power connector, an additional 4- or 8-pin CPU power connector, and PCIe power connectors for graphics cards.

Compatibility and use: ATX boards are designed to fit into ATX-compatible cases and share common mounting holes and I/O layout, enabling broad interchangeability among vendors. While newer form factors exist, ATX remains the prevailing standard for desktop PCs, balancing expandability with cost and compatibility.