The ATX form factor was created by Intel in 199i It was the first big change in computer case an, motherboard design in many years. A TX overtoc AT completely as the default form factor for ne systems. Some related designs include mini-ATX and micro ATX. ATX addressed many of the annoyances with the AT form factor that system builders had! put up with. ATX form motherboards are becomm. increasingly popular because of their advantages over theolder AT motherboards.
AT-style computer cases had a power button that directly connected to the system power supply JIt(PSU). The general configuration had four pins 'lat had to be connected individually. Sometimes, 'le pins were soldered to the power button, making 'difficult to replace the power supply if it failed, or the fan inside the PSU seized up. The A TX version the power supply didn't directly connect to the stem power button, allowing the computer to be powered off via software. However, many ATX power supplies have a switch on the back to ensure no power -flowing to the motherboard.



The power supply's connection to the motherboard was changed. Older AT power supplies ad two similar-looking connectors that could lmetimes inadvertently be plugged in incorrectly, generally causing short-circuits in the motherboard nd causing it to fail. ATX used one large keyed mnector instead, which made installation much asier and safer. However, the amount of power Jelivered fell below the requirements of newer AGP video cards and faster processors such' as Intel's Pentium IV and Athlon from Advanced Micro Devices (AMD), so some auxiliary power connectors were eventually added to the standard.

On the back of the system, some major changes ere made. The AT standard only had a keyboard connector and little else. Other common data . mnectors such as serial and parallel ports had to beaunted individually. ATX allowed each motherboard manufacturer to put these ports in a rectangular area on the back of the system, with an arrangement they could define themselves. To avoid any gaps in the case, each manufacturer provided their own rear panel that could be inserted to fill any unused space. The A TX form factor uses a 20-pin power connector located on the motherboard. The newest A TX specification uses a 24-pin power connector to support the power requirements of PCI Express.