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PC turning off, not turning on.

Discussion in 'General Hardware' started by Shedman, 15 Apr 2010.

  1. Shedman


    Joined: 10 Aug 2009

    Posts: 101

    The other day my PC just switched off like there was a loss of power or something. A few seconds later it came back on but only for 10 or so seconds and switched itself back off.

    The motherboard does post but sometimes it can shut itself off almost instantly after pressing the power button and other times it can shut off after a few hours.

    I don't think the cpu is the problem as it is stable after 30 runs of IBT before this problem occured.
    I have ran memtest and found no errors in both sticks.

    The PSU, when shorting the green and black wires on the 24 pin connector does not shut off when a few fans are just plugged in.

    My guess was that it was either the the motherboard or PSU but since the PSU can power a few fans without shutting off and does not shut off when under load before.

    After it has shut off I have to flick the swith on the wall socket or the PSU and wait for the power to drain from the PC ( around 3-4 seconds) for the PC to turn back on, I think this points to a motherboard fault.
  2. acharris


    Joined: 13 Aug 2004

    Posts: 816

    Hey, I would try a known working PSU first before the mobo, as this sounds like a PSU fault and turning off at the mains is resetting the PSU or something along those lines. My PC in sig was stuggling to power up, but when it did it would be fine and I could leave it on for 18 hours a day and play a few games with no problems

    Then after 3 - 4 days it would stuggle to start up from either sleep or powered off, then one day it would not turn on only for about 2 secs off, 2 secs off for the fans to spin then die. Tried the PSU with 2 fans connected, no problems powered ok. tried a cheap £30 psu for testing and powered straight up no probs.

    Then bought a Antec Truepower 650w and no power problems since. Deffo sounds like PSU issues.
  3. NutterzUK


    Joined: 18 Feb 2010

    Posts: 936

    I can't see it being your motherboard. Do you move the system around often? The fact you have to switch switches etc to drain power to get it up and running again to me screams that it's the PSU. Surely if it was any kind of issue with the motherboard you'd see problems booting all the time.
    Cheap fix would be to borrow a PSU from another comp, it's easier than changing the whole MB too.