Power supplies are needed because your computer needs different voltages than what comes straight from the outlet. Disconnecting and replacing a power supply is simple because it's just piece of hardware.
1). Shut down your computer and unplug the cable from the wall and the back of your computer. Open the computer case. This may involve unscrewing the access door from the back of the computer, pushing a lever or just sliding the door off.
2). Unplug the power connectors from all of the drives and the motherboard. The connectors can be removed by either pulling them straight out or by pushing a release button first and then pulling the connector out. Some motherboards have two sockets where the power supply is plugged in.
