You will need
  • Work computer, clip, screwdriver, multimeter.
Take another working computer. Carefully disconnect the wires from the power supply and remove it. Connect the power supply to check. And try to start the computer. If it does not turn on, recheck the proper connection of all wires and start again. If the computer does not turn on again, then your power supply is burned.
If you don't have another computer, remove the PSU and open it. Carefully inspect everything inside. If you see swollen capacitors, smelled or saw Gary spilled a sticky liquid on the motherboard, then your power supply is burned.
If the inside no damage is detected, it is necessary to try to run the power supply separate from the computer. A large part of the power supplies are equipped with load resistors (the exception may be some Chinese models), so the hot wire and test the power supply to be safe.
Put the PSU on the floor and check that under it there were no metal objects. Take the ribbon cable that connects to the motherboard, select the black and green wire. Lock usual a paper clip both wires. Instead of a paperclip you can use any metal object. If the power supply is switched on (earned cooler, turn on the led of the drive), so the problem is not in it. This is the easiest way to check power supply for proper operation.
Next, you will need to check the voltage on all outputs of the PSU. It is of 3 types - +3.3 V (orange), +5V (red and white), +12V (yellow and blue). Better before testing, connect the power supply small loads, such as automotive light bulb. Take a multimeter and connect it alternately to each output. Before checking all the connectors better purging to remove accumulated dust. Slight variations in voltage are permissible. If deviations are more than 0.5 V, then the problem is in this place.