Short for Advanced Technology eXtended, ATX is a specification used to outline motherboard configuration and dimensions in an effort to improve standardization. First released in July of 1995 by Intel, ATX has since had many revisions. The first was version 2.01 in February 1997, then 2.03 in May 2000, 2.1 in June 2002, and 2.2 in February 2004.
ATX boards didn't hit the market in force until mid-1996, when they rapidly began replacing Baby-AT boards in new systems. The original ATX motherboard, often referred to as Standard ATX or Full-ATX, is 12" wide x 9.6" deep (305 x 244 mm). Its COM port, LPT port, PS/2, and USB are mounted directly on the motherboard. The image below is an example of the ATX form factor.
Advantages of the ATX motherboard
- The ATX motherboard includes advanced control facilities, where the BIOS program continually checks the CPU temperature and voltages, the cooling fans RPM, etc. If overheating occurs, the PC will shut down automatically.
- The ATX motherboard has a stacked I/O connector panel mounted on the motherboard.
- On a socket 7 ATX motherboard, the socket has been placed a further distance from the expansion slots, allowing for long boards to be placed in easier.
- ATX 2.01 includes a single keyed, Molex internal power supply connector which cannot be placed improperly. However, its standby voltage needs to be greater than 720 mA. While the Molex power connector allows for 5v and 3.3v to be connected, it is recommended that only a 3.3v be used.
- Relocation of the memory and the CPU allows for better ventilation and easier installation.
- Power management is now possible with proper BIOS support.
- The PC can also be turned on by a modem or network signal, since the power supply is controlled by the main board.
- The computer cannot be turned off as the computer boots. However, if the computer freezes as it is turning on you can turn off the computer by holding the power button for five seconds.