EATX

Extended ATX (E-ATX) is a motherboard form factor larger than the standard ATX. The common dimensions are 12 inches by 13 inches (305 by 330 millimeters). Unlike ATX, which has a standardized mounting hole pattern, E-ATX boards vary by manufacturer and generally require a bigger chassis and additional mounting points.

E-ATX boards typically offer extra PCIe expansion slots, more memory slots, and additional storage and I/O options. This supports high-end desktops, workstation builds, and systems that need multiple GPUs, more RAM, or specialized peripherals. Features such as enhanced power delivery, larger heatsinks, and additional M.2 or USB ports are common, but specifications vary by model and vendor.

Compatibility and considerations: Because of their larger size, E-ATX boards fit only in cases that explicitly support E-ATX or larger formats, such as full-tower or workstation cases. Users should verify case compatibility, including motherboard tray mounting, interior clearance for CPU coolers, PCIe card length, and GPU clearance. Power supply positioning and cable routing can be more challenging with wider boards, so planning airflow and component layout is important.

Summary: E-ATX serves users who need extra expansion and customization beyond ATX, including enthusiasts and professionals requiring multiple PCIe cards, increased RAM capacity, or specialized I/O. It remains popular for those workloads but requires a compatible case and components, and can increase system size and cost.