ATX Size report
ATX (Advanced Technology Extended) refers to the motherboard specification formulated by Intel Corporation in 1995. It is the first major change in the design of computer cases and motherboards in years. ATX replaces the AT motherboard specification as the default motherboard specification for newer computer systems, which solves the problems from the past AT specifications.
ATX has seven expansion slots. Other derived motherboard specifications, including microATX, and mini-ITX, retain the basic ATX backplane setup, but the motherboard area is reduced, and the number of expansion slots is also reduced.
When your CPU, motherboard, and graphics card are replaced repeatedly, maybe the chassis and power supply you bought may still be serving you silently. First of all, you need to pay attention to the size of the motherboard. This post explains more basics about the ATX motherboard size.
ATX Size Guide
Since Intel published the original ATX official specification in 1995, this specification has undergone several changes; the latest specification, ATX12VO, was released in 2020. The standard ATX console version is 12 inches long and 9.6 inches wide (305 mm x 244 mm). This also allows standard ATX cases to accommodate smaller microATX motherboards. In 2003, Intel released a new BTX motherboard specification as an alternative to ATX. However, the ATX specification is still the most popular motherboard specification for assembling computers due to compatibility issues. Only the retail computers of large manufacturers use BTX. Therefore, Intel gave up the development of BTX in 2006.
Picking a right-sized motherboard is one of the most crucial tasks while building a new PC. The kind of motherboard you pick highly affects the PC's performance since all sizes of motherboards come with different numbers of expansion slots and support different kinds of hardware.
Standard ATX Dimensions
There are many sizes of computer motherboards. These three form factors often refer to PC cases themselves, but the terms more accurately refer to the size of the motherboards they can host. There are also larger sizes: EATX (Extended ATX) and XL-ATX; smaller sizes: Nano-ITX and Pico-ITX.
- ITX (Mini-ATX): 6.7" x 6.7", 170 mm x 170 mm
- M-ATX (Micro-ATX): 9.6" x 9.6", 244mm x 244mm
- ATX: 12" x 9.6", 305cm x 244cm
- EATX: 12" x 13", 305mm x 330mm
- XL-ATX: 13" x 10.4", 330 x 264mm
Common Motherboard Sizes
| Features | ATX | EATX | Micro-ATX | Mini-ITX |
|---|---|---|---|---|
| Max Size | 12" x 9.6" | 12" x 13" | 9.6" x 9.6" | 6.7" x 6.7" |
| RAM Slots | 2 to 8 | 2 to 8 | 2 to 4 | 2 |
| RAM Type | DIMM | DIMM | DIMM | DIMM, SODIMM |
| Expansion Slots | 4 to 7 PCIe Slots | 4 to 8 PCIe Slots | 2 to 4 PCIe Slots | 1 PCIe Slot |
| Graphics Card Slots | 1 to 4 | 1 to 4 | 1 to 3 | 0 to 1 |
| SATA ports | 4 to 12 | 4 to 12 | 4 to 8 | 2 to 6 |
Final Words
A computer case supports only a corresponding motherboard size, but if the case is backward compatible, it can be matched with more than one motherboard. For example, most ATX-compatible cases will accept a MicroATX or Mini-ITX board. Generally speaking, a case that supports a larger board tends to be larger than one that supports only smaller boards, but this is not universally true. Also, note that a case that supports a given motherboard size likely supports the smaller motherboard form factors, too, although that is required verifying in a case's specifications before buying.
