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I have a PC which is randomly shutting off (the hard way, like someone pulled the plug). It's no heat problem, because this can happen after 2 minutes of operation or after 4 hours and I checked the temperature. It's also no problem of the operation system, because it will also do that while in BIOS. If it happens once, you can be sure that it will happen within the next hour another two or three times, and then it works again for over a week or even longer.

Possible causes I've thought about so far are:

  • Voltage Fluctuation
  • Loose contact (already replugged all cables within the PC, no luck)
  • Faulty PSU

Maybe someone has more ideas to this?

P.s.: I don't have the hardware specs with me right now, I'll post them as soon as I get them.

Edit: Confirmed btw, it was the PSU.

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My guess would be either a faulty power lead or a loose power connection from the wall socket to the PC. – ChrisF Mar 14 '10 at 22:13
my inclination would be to swap a known-good PSU in and use that for a while (maybe as much as a week or three, if you have no direct means of triggering the problem). if after 3 weeks the problem hasn't recurred, blame the old PSU and move on. – quack quixote Mar 14 '10 at 22:23
Most likely the PSU – anon31097 Mar 18 '10 at 17:48
+1 for reporting back that your issue was the PSU. I'm having similar symptoms and have ruled out several other (cheaper) points of failure including the physical power cord, my UPS, and the wall outlet, so I'll focus on the PSU next. Thanks! – Jon Schneider May 4 '12 at 23:16
up vote 4 down vote accepted

You could install CPU-Z ( to monitor your voltages while the machine is on. Perhaps your PSU has a low tolerance for line voltage variances. You could purchase a P3 Kill-a-Watt from Newegg (about 25USD when i bought mine a few years ago). This has many other uses besides monitoring line voltage. There also PSU testers out there but those can be pretty expensive. I would first try CPU-Z then try switching in a known-good PSU.

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