Most computers that are sold feature a standard form factor motherboard.
In 1995 these standards were replaced by an Intel-developed standard, ATX, that is still used today.
To some degree, this has enabled alternative layouts that can be more space efficient or improve airflow.
It is less friendly towards the standard home user.
The driving concept of the proprietary form factor is demonstrated by the use of non-standard connectors.
Contents
ATX
The ATX motherboard standard has been in place since 1995.
While the individual components have changed as technology and connector standards have changed, the overall average hasnt changed.
For example, the motherboard still uses the same standard size of 305mm x 204mm.
Another critical point is the mounting points.
Or a 1995 ATX motherboard into a modern case with no issues.
This standardization means that any compatible PC case will fit any ATX motherboard.
For example, users dont need to peek if the rear I/O plate is too large.
It also means that other components will just fit.
For instance, A GPU will fit and align with the rear access panel.
Large components like the CPU cooler can be designed to allow for the proximity of the RAM.
This is generally used in small form factor computers.
The reduction in size does mean some components need to be sacrificed.
Typically, these are PCIe expansion slots.
The smaller size also somewhat limits the cooling capacity that might be achievable in a more significant case.
A key difference of MicroATX is that the motherboard mounting screws have different locations.
Some but not all full-size cases offer secondary mounting points for MicroATX motherboards.
EATX is a relatively loosely defined standard that simply covers motherboards that are larger than standard ATX motherboards.
A key point is that the mounting points are the same as for ATX motherboards.
Care should ensure that cases offer enough space to fit the larger EATX motherboards.
Some EATX motherboards may offer dual CPU sockets.
ITX
There are three ultra-small form factor motherboard standards: MiniITX, NanoITX, and PicoITX.
These are compatible with x86 CPUs and could be used for small form factor computers.
However, these are typically used in industrial and automotive control systems.
Conclusion
ATX has been the standard motherboard form factor for PCs since 1995.
