Motherboards Explained: What is ATX, MicroATX, and Mini-ITX?
Hardware standardization is one of the greatest strengths of desktop PCs. You can mix and match parts to your heart’s content. But not all motherboards are the same physical size. There are different form factors for different types of PCs.
Different Standards
Just like other PC components, motherboards have standardized form factors, including ATX, MicroATX, and Mini-ITX. Nearly every motherboard for home computers at your local PC shop or online will be in one of these flavors.
Standardization means you can easily find a processor, RAM, power supply, and storage that works with your motherboard. It also opens up the choices for desktop PC cases. Numerous cases support all three of the major motherboard sizes. The mount points are drilled into the appropriate spots, and the proper space is available for the rear ports and accompanying I/O shield that covers them.
It’s a beautiful thing, but to decide which motherboard is right for you, you have to consider things like space, and your experience building PCs and performance needs.
PC Motherboards: The Basics
Intel created the ATX form factor and first introduced it in 1995. For nearly 25 years, the ATX design has been the predominant form factor for home and office PCs.
The largest of the three motherboard sizes we’re looking at, the ATX measures 12 inches by 9.6 inches. The specification requires all ATX motherboards to be this size. It also specifies the locations of the mount points, the I/O panel, the power connectors, and all other various connection interfaces.
All these features are crucial for any motherboard. The mounting points keep the motherboard away from the case’s metallic surface to prevent electrical shorts. The I/O panel and accompanying shield allow you to access your PC’s rear ports for displays, audio, and USB. Then, you have the power connectors and all the other interface points that must be in predictable locations to aid system builders.
However, not everyone wants an ATX-sized motherboard—especially if the goal is to make something more compact. Enter, MicroATX boards, which measure just 9.6 inches by 9.6 inches. Like the larger ATX motherboards, the standard determines what all the various critical points must be.
Finally, the Mini-ITX, developed by Via Technologies in 2001, is the smallest of them all, measuring a mere 6.7 inches by 6.7 inches.