When I moved house I set up my computer and when I plugged the power cord in I noticed it was sitting a bit loose but I ignored it. Last night I was on my computer and when I stood up I kicked the power cord. I heard a static sort of sound and now my computer won't turn on. The LEDs aren't glowing and the fans not moving.

Do I need to replace the power supply?

  • 1
    Did you check the fuse?
    – Tetsujin
    Commented Feb 5, 2016 at 18:29

1 Answer 1


First, check the connections are okay, the power to any power strips are working, and the cable itself is okay including fuses.

You can test whether the power supply has died by removing the 20(+4) pin connector from the motherboard, and shorting the GREEN wire pin to any BLACK wire pin.

Green To Black Shorting

Connector PinOut Diagram

Upon doing this, the PSU should kick into action (any LED if present and fans should come on, as well as power rail outputs), and you would be able to measure 12v from a YELLOW to a BLACK wire, and 5v from a RED to a BLACK wire.

If the PSU doesn't react at all to this, the PSU is dead and will need replacing. If the PSU does react, you can try bridging the pins on your motherboard corresponding to the PWR_SW / POWER_SW. If that doesn't work, it's most likely the motherboard itself has a problem.

  • Out of curiosity, how do you short a green pin to a black pin? This seems like an excellent way to test a PSU as long as you have a multi meter laying around. And by kick into action do you mean the fans turn on?
    – DrZoo
    Commented Feb 5, 2016 at 19:13
  • @DrZoo Not sure if my terminology is perfect :) A paper clip between the two is how I usually connect them. And yes, LEDs (if present) and fans should come on, on the PSU.
    – Jonno
    Commented Feb 5, 2016 at 19:16
  • Ah I see! I wasn't sure if that's what that was in the picture or not lol. I'll have to keep this trick in my books! Hopefully I don't make sparks :)
    – DrZoo
    Commented Feb 5, 2016 at 19:25
  • Wouldn't a simpler way be to just go to a local computer or online and get a power supply tester, they are cheap ($5 for a simple one with just LEDs, or $10 for ones with a digital display showing all rail voltages), or just pull the power supply and run it into your local PC shop and ask them to test it quick? It would also give you a more exact answer
    – acejavelin
    Commented Feb 5, 2016 at 20:27
  • 1
    @acejavelin Define simpler ;) If you already have a multimeter it's not going to give you a more exact answer than that, and you can diagnose the PSU in under a minute. Honestly, if the PSU doesn't even turn it's own fan on, there's no point using any tester on it. I'd say it's down to opinion from there, I'd rather have one tool that does many jobs, than buy specific testers for different purposes. Each to their own though :)
    – Jonno
    Commented Feb 6, 2016 at 5:32

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