1, ATX 20-pin plug is mainly some of the old computer power supply, belongs to the ATX12Vv1.x version of the specifications, and the motherboard 20-pin plug connected to the motherboard to provide the motherboard with a 3.3V memory power supply voltage. 12V motherboard and ancillary equipment (hard disk, graphics card, etc.) power supply voltage. 5V voltage.
2. To test the switching function of the ATX power supply individually, simply short 7 and 8 pins with a small copper wire.