MOTHERBOARD SIZES: E-ATX, ATX, MATX EXPLAINED

The most common motherboard form factors are E-ATX, ATX, and MicroATX (mATX). Choosing the right motherboard is one of the most important decisions when building a PC, as it determines case compatibility and influences available features such as expansion slots, storage options, and connectivity.

Here is a quick overview of each form factor and how they differ.

ATX

ATX is the most widely used form factor in most consumer PCs. It has a standardized maximum size of 305 x 244 mm (12" x 9.6") and fits in most mid-tower and full-tower cases.

ATX motherboards are available across a wide range of price tiers and feature sets, from entry-level models with basic connectivity to high-end boards offering extra PCIe cards, M.2 storage, and robust power delivery.

E-ATX

Extended ATX (E-ATX) motherboards are larger than standard ATX, and usually packed with features, including advanced connectivity and expansion options. They typically measure around 305 x 330 mm (12" x 13"), although width and layout can vary depending on the manufacturer.

E-ATX boards are often found in servers, premium workstations, and enthusiast builds. They require cases with explicit E-ATX support, such as the VALOR AIR PRO, so it is important to verify case compatibility and exact measurements before purchasing.

mATX

MicroATX (mATX) motherboards have a maximum size of 244 x 244 mm (9.6" x 9.6"), making them slightly smaller than standard ATX.

mATX boards are commonly used in both compact builds and standard ATX cases. They may offer fewer expansion slots and connectors than ATX boards but still provide enough features for most gaming and general-purpose systems. Case compatibility and component clearance (GPU length, CPU cooler height, radiator support) should always be checked, especially with smaller cases like the VALOR NANO series.[1范1] 

Another widely recognized form factor is mini-ITX, which measures up to 170 x 170 mm (6.7" x 6.7"). This is the go-to motherboard for small form factor PCs, but comes with trade-offs such as limited expansion slots and can more challenging cable management and cooling.

ATX VS. E-ATX VS. MATX: WHICH IS BEST FOR YOU?

Deciding on other components before the motherboard is common, but it is important to make them all work together.

Compatibility

You can almost never go wrong with an ATX motherboard. They are compatible with most  standard cases, making them a safe and flexible choice for many builds. However, exact case specifications should always be checked, especially for radiator support and cable clearance. E-ATX boards require cases with specific support, while mATX boards fit in both ATX and mATX cases.

Expansion

ATX and E-ATX motherboards typically offer more M.2 slots, SATA ports, and I/O options. mATX boards often trim back on these features to accommodate their smaller size, though higher-end models can still provide strong connectivity.

Clearance

Larger motherboards can affect internal case clearance. E-ATX boards may reduce cable routing space or obstruct grommets, and require a spacious PC case. mATX boards are often used in smaller cases where component compatibility needs to be carefully checked.