Before removing a PC power supply, make sure that the computer has been removed from power. In order if it is carrying a residual voltage in the power supply, you must push the power button-on. However, be careful, because the PC power supply unit can store up to 5 minutes after it’s cut off from electricity. Don’t damage the sensitive components, for example by touching it, one must be grounded on a heating pipe.
In order to supply the PC, disconnect all the plugs. Then you can remove the four screws at the rear of the case. Now remove carefully.
If a PC power supply has been installed in the right place, you can now connect to the individual components. First, the main power connector plugged into the motherboard. Standard model has 20-pin connector. For high-power devices are available in some PC power supplies have an additional 4-pin connector.
Installation of other components explain almost by itself drives and graphics cards are supplied with different connector types.Right here you just have to find a suitable plug connection.
if you are still confused, you can try to read the article step by step How to Install Computer Power Supply.