This illustration provides a closer view of the ATX form-factor power supply connection on the motherboard. Look closely at the connector, the holes are keyed. By incorporating keyed slots, the power supply can only be connected to the motherboard the correct way. The power supply cannot be connected incorrectly with these keyed slots.

When used with a power supply that supports remote power on and off, the motherboard can turn off the power through software control. The Powerman utility supplied for Windows® 3.x allows for soft off as does the shutdown icon in the Windows® 9x Start menu. The BIOS turns off the computer when it receives the proper Advanced Power Management (APM) command from the operating system. For example, Windows 9x issues this APM command when clicking Shutdown the computer. APM must be enabled in the BIOS Setup Utility and the operating system in order for the soft-off feature to work correctly. In order for the computer to recognize the presence of a soft-off power supply, the supply must tie pin 14 of the PWS Control connector to the ground. If power to the computer is interrupted due to a power outage or the power cord being unplugged, when power is reapplied, the computer returns to the state it was in when the power was disconnected. If the computer was turned on when power was disconnected, the computer turns on again when power is reapplied.