Molex connector on an ATX power supply.
The advanced technology extended (ATX) standard is one of the most widely used form factor in computer systems today. Over time, the ATX standard has been modified to include several different versions including ATX and ATX12V (ATX v. 2.0+).
ATX Power Supply
One of the distinguishing characteristics of the ATX power supply is that it uses a single 20-pin connector as the main power connector. The ATX power supply come with three different power connectors: +3.3V, +5V, and +12V. The 4-pin 12V connector, supplies power exclusively to the processor, while the 6-pin auxiliary power connector carries +3.3V and +5V voltages for other components. The +5V connector allows ATX power supplies to carry Standby and Power On signals enabling the operating system to perform a soft power shutdown.
ATX12V Form Factor
The ATX12V power supply contains a 2 x 12 (24-pin) power connector. The 25-pin connector supports the 75 Watt PCI Express requirements and it is backward compatible. It also contains an additional 12V rail for components requiring greater than 18 amps of current.
Additional Differences
The ATX12V power supply standard eliminates the auxiliary power connector. Minimum efficiency ratings on the ATX12V power supply are greater than the ATX power supply.
Tags: power connector, power supply, ATX12V power, auxiliary power, auxiliary power connector, connector power