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Computer shuts off randomely & won't boot until left unplugged.

Hi.

So my PC randomly shuts off,it may be after a hour of using or a minute.

When I press the power button it does nothing until it's left unplugged and then when plugged back in will work for a while and shut off randomely.

Few days ago I removed a unused sata cable and it worked perfectly for a week.

Now it's back to how it was.

Help please
24 answers Last reply Best Answer
More about comouter shuts randomely boot till unplugged
  1. What you describe sounds like a faulty PSU or motherboard. Removing the Sata cable is more likely a coincidence. What's your full pc spec including make and model of psu
  2. Thanks for the reply.

    My specs are-
    GTX 670
    Gigabyte z68xp-ud3p Mobo
    16gb vengence ram
    ocz 750w power supply!
    I7 2600k
  3. Powersupply is the OCZ ZS750W
  4. When I loaded it up there is said main bios checksum error?
  5. Ok I'm not sure what that is telling you but it rules out a PSU problem, I am thinking a motherboard problem but am not sure
  6. Severe overheating?
  7. Still looks like a PSU problem or overheating problem. BIOS checksum error is likely from the random power offs. This can be corrected by entering and exiting BIOS if I recall to confirm settings.
  8. All my temperatures are okay as I checked myself.

    Any way I could break this down more and target what it might be?

    Don't want to buy a new mobo then need to get new PSU.
  9. To be honest, overheating or PSUs are the only things I know of hardware wise that can cause a complete random power off. I could see the motherboard causing a BSOD/reboot or being "flaky" with odd behavior or something along those lines, but I've never heard of one being the cause of a power off. You could also check the voltage of the PSU if you have a DMM around. You should be able to disconnect the power supply from your motherboard, drives, ect. and check voltages using the paperclip test to "start" the PSU, unless you happen to have a PSU tester.
  10. Run "cmd" as administrator and do this command:
    sfc /scannow
  11. Thanks for all the help so far guys.

    I while back I over clocked my PC a tiny bit I think,I should reset it to default and see if that does anything.

    I will also try that command later and let you know how I get on.At work now.

    Really appreciate the help.
  12. Hey people,on my computer now and running the "sfc /scannow" command.Anything else I should do while its on?
  13. An overclock can actually cause a shutdown. I have seen this myself when making OC adjustments to my cache speed. It's a good idea to reset back to stock while figuring out this problem. How did the sfc /scannow go?
  14. Thanks for all the help 1LiquidPC,Ive tried to reset to facrotry settings but dont think it worked.Ill try again when I'm home,I think i done the "Return to fail safe defaults" - is that factory reset of bios?

    The sfc /scannow found no proplems or errors.
  15. The "reset to defaults" should do just as it sounds. However, some folks insist removing the CMOS battery itself from the motherboard is the true way to clear the BIOS. Have you considered the PSU test idea I mentioned earlier to check voltages? The readings in the BIOS itself should give you a rough estimate though. About 5% is the tolerance for ATX spec for 12v, 5v, and 3.3v.
  16. You do have a surge protector right?
  17. Yes I got it reset to defaults last night and still shut off randomely.

    I think I may need need to test the PSU and check the voltages.

    What would i need to buy to do so? A DMM right?

    Atleast then I would know its my PSU and could just replace it.

    I do have a surge protector,it did start to mess up tough in recent times and started to struggle to turn on.So I have been trying to fix the PC without it as its so tempermental I've just been plugging into the wall.

    I must purchase a knew one today.
  18. A cheap DMM from Harbor Freight or something similar should be fine. This guide should help though there should be plenty of others. http://www.tomshardware.com/reviews/power-supply-protection-calculate-consumption,3066-6.html. Also, its possible that the voltages look good, but there can still be a fault in the PSU.
  19. So I just done the paperclip test to see.It does exactly what's wrong.Stays on for a tiny bit and then won't start again.All the fans came on for like 30 seconds and then went off.Then tried to turn back on and it would not.

    Safe to say my PSU is dead?
  20. Sounds like the culprit to me. I've used the paperclip test quite a few times over the years, and never seen it not respond to the power switch. Also, when toggled on using the switch, it would stay running until I manually shut it off. Also to be sure, you didn't have the PSU plugged into anything except a fan or two when testing, correct?
  21. Thanks for the information.

    I'm very confident that it's the PSU now it shuts off the same way and kinda makes the same noise.

    Like 4 fans and that was it? I might try isolate it more maybe just to be safe but pretty sure that's the culprit.
  22. I had everything disconnected bar the 8pin as it's so annoying to reach as it's behind my heatsink but online it said that's okay to leave in?

    Is that okay?

    Thanks for all the help so far.
  23. Plugged it out and same thing.

    Going to buy new PSU now :)
  24. Best answer
    It sounds like its the problem after further diagnosis. Just be sure to select a reputable make/model PSU. The PSU Tier list should offer some guidance. http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html
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