A failing power supply can be the source of many computer crashes. It can also result in hardware that operates poorly or not at all. A failure to recognise the real problem means hardware is often replaced rather than the power supply itself. Testing your Dell power supply to see whether it still works is a simple process that you can accomplish with a paper clip. When a paper clip is connected to the green (signalling) wire and a black (ground) wire, it completes a self-test circuit that will turn the power supply on if it passes the test or prevent the power supply from turning on in the event of a failure.
Unfold the paper clip into the shape of a "U."
Remove the Dell's side access panel. This may require the removal of one or more thumbscrews on the rear face of the computer's case.
Disconnect the main motherboard connector of the power supply from the motherboard. This will be a 20- or 24-pin rectangular connector. This connector is the largest coming from the power supply and is connected to the motherboard just to the right of the computer's central processing unit.
Locate the pin on this connector that is connected to a green wire. There is only one, and it lies between two connectors attached to black wires.
Insert one end of the paper clip into the green wire's connective socket.
Insert the other end of the paper clip into either one of the black wire sockets located directly next to the green wire.
Plug in the power supply and press its external or main power switch to the "On" or "Closed" position.
Listen to the power supply. If the fans turn on within the power supply, it has passed all self-diagnostic tests and is still working.
There is zero chance of electric harm during this procedure as long as the ends of the paper clip are in the correct sockets. This green wire carries only a minute signalling voltage that allows the power supply to turn on if there are no hardware failures.