Desktop Power Supply
Knowing how to properly install computer power supply units begins with a review of safety. Your new power supply has plugs that will power the computer as well as various devices in your desktop. Handle it with care, and be very careful not to poke around in its vents with any objects.
Your power supply also has the ability to retain electric charges even after you've unplugged it. It's good to know these things in advance so we don't make any foolish mistakes.
Now the first order of business is to remove the case. The method for doing this will vary depending on your system. If you have a mini-tower, then unscrew the side panel above the motherboard and slide it off. Set the screws in a safe place. If you have an older model of computer, then you will probably have to unscrew the whole back cover, and completely slide the chassis out.