1. Plug the 24-pin or 20-pin main ATX keyed power supply connector into the motherboard
power socket. You can plug a 20-pin connector into a 24-pin socket (and vice versa) by connecting
them in an offset fashion, or you can use cable adapters to mate them up. Most ATX systems
also use a 4-pin or 8-pin ATX12V connector. These are also keyed and plug in only one
way (see Figure 19.25).
2. Connect a power lead from the power supply to the CPU fan if the motherboard does not have
a CPU fan power connector.