AT vs ATX
The motherboard is an integral part in a computer since it is where all the components are attached to. ԬThere are many standards for motherboards and the cases that holds them. The most prominent standards are AT and ATX. AT is a very old standard that was created by IBM for their own computers. ATX was developed by Intel to address some of the shortcoming of the AT standard that makes it unsuitable for the varied demands of personal computing.
AT boards were much bigger compared to ATX boards. This results in some drives overlapping the boards inside the case which meant that in order to replace the board, you would need to take everything out. This is very inconvenient for personal computers, thus the ATX boards were made narrower by almost 4 inches to ensure that there is no overlap.
Another shortcoming of the AT system is in the ports at the back. AT boards only had the most minimal amount connectors in order to maintain compatibility with AT cases. If you like more connectors, you would need to add flying leads to unused expansion slots. ATX cases allowed manufacturers to produce their own custom backplates to suit their motherboards. This allowed most ports to be integrated to the board and moved up, making it much less of an effort to install a new motherboard and even frees up some of the expansion slots taken up by the ports.
ATX boards also introduced the ‘soft off’ capability. Prior to ATX, the power switch was directly connected to the power supply and the computer cannot turn itself off. ATX cases moved the switch to the motherboard. Computers then had the ability to turn itself on or off depending on its programming. You would no longer need to wait for the computer to safely shutdown before turning it off. It also paved the way for the additional features like WOL (Wake On Lan) that allows computers to be turned on remotely via its network adapter.
Summary:
1. AT is an old standard that has been totally replaced by ATX
2. AT boards are wider compared to ATX by almost 4 inches
3. ATX allows board makers to customize the ports in the back with backplates which is not possible with AT
4. AT computers had their power switches connected directly to the power supply while in ATX systems, the switch is connected to the motherboard