When you first learn how to build a PC, everything can seem very complicated, and one of the most confusing aspects is the size of the motherboard. Depending on the type of case you buy for your build (and generally what kind of hardware you’re going to put in your computer), there are different size options. Below we’ll explain the main versions of modern motherboards and what they mean.
Want to learn more about gaming and PC gear? Check out our guides to the best gaming keyboards, best gaming mice, best gaming headsets and best gaming controllers.
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What is ATX?
Why do most modern computer motherboards look the same? It’s because almost all of them use ATX. ATX is a standard that defines the size, position and power delivery of motherboards, power supplies and desktop cases. This set of rules ensures that all components work together, regardless of manufacturer.
For our purposes, we’ll focus on physical dimensions. Some elements, like the size and location of ports on the rear, are consistent across all ATX variants. Other aspects of the standard, like the width and length of the board, are denoted by their own acronyms to help you quickly identify size and compatibility.
ATX only
Photo: Amazon
ATX is both the name of the standard and the most common size designation. If you’ve ever opened the side of a computer case, the form factor will be familiar to you. At 305 x 244 mm (12 x 9.6 inches), motherboards of this size have enough space to accommodate four or more RAM slots, multiple PCIe cards of various lengths, and two to four M.2 slots.
for example: ASUS TUF Gaming B650-Plus WiFi ($200) It is a full-size ATX motherboard for the AMD AM5 platform, with four RAM slots, two M.2 slots, and one PCIe 5.0 slot.
They’re perfect for basically any PC build, from a simple living room email checker to a powerful gaming rig. They’re usually the first to be released when a new generation hits the market, and they have all the new features and options without paying the premium price. ATX motherboards come in a wide range of budgets and feature sets, so you don’t need an expensive computer to enjoy their benefits.
MicroATX
Photo: Amazon
A slightly smaller option, Micro ATX (or mATX for short), is becoming more and more common as it is constantly improving in energy and thermal efficiency. These boards are the same width as full-size boards, but are shortened on one side to a 244 x 244mm square. They also have many of the same options and features as ATX boards, and are not quite as expensive, making them a popular choice for mid-range gaming PCs.
for example: Reasonable price MSI Pro B760M-P ($99) It only has a CPU slot for the latest generation Intel chips, a PCIe 4.0 slot, and one M.2 slot.
