Rapid power cycling

Hello, I just built a very powerful computer with a Core i7-990X, an EVGA motherboard with an Antec 1200W power supply. The system was functioning fine for a few days, but after a restart the computer will not turn on. At first, it froze at the POST screen, but now it turns on and power cycles every three to five seconds. We have also noticed that one fan, connected directly to the power supply with a Molex connection does not spin when the computer boots.
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More about rapid power cycling
  1. Hmm I want to say it might be as simple as a stuck power switch, but given that it worked before that is probably not the problem.

    Are you overclocking?

    My first inclination would be to pull out the PSU, short the 20+4 connector and check all the rails with a multimeter.
  2. singemagique said:
    Hmm I want to say it might be as simple as a stuck power switch, but given that it worked before that is probably not the problem.

    Are you overclocking?

    My first inclination would be to pull out the PSU, short the 20+4 connector and check all the rails with a multimeter.


    We are not overclocking the computer, but we might try your tip. Could the motherboard be bad?
  3. singemagique said:
    Hmm I want to say it might be as simple as a stuck power switch, but given that it worked before that is probably not the problem.

    Are you overclocking?

    My first inclination would be to pull out the PSU, short the 20+4 connector and check all the rails with a multimeter.

    ^+1 also check your case reset button
    I've seen many of these stuck in the on position.
  4. davcon said:
    ^+1 also check your case reset button
    I've seen many of these stuck in the on position.

    I don't think that the reset button is stuck because before the power cycling happened, the computer froze at the POST screen and would not boot. I believe, according to the little LCD on the motherboard, it was stuck at checking the memory
  5. rabbatiello said:
    I don't think that the reset button is stuck because before the power cycling happened, the computer froze at the POST screen and would not boot. I believe, according to the little LCD on the motherboard, it was stuck at checking the memory

    Download http://www.memtest.org/
    Create a bootable cd/dvd or usb
    Start by checking one ram module at a time.
  6. davcon said:
    Download http://www.memtest.org/
    Create a bootable cd/dvd or usb
    Start by checking one ram module at a time.

    Unfortunately, I cannot run this utility because the computer will not boot, it cycles very quickly every three to five seconds with no output on the display.
  7. rabbatiello said:
    Unfortunately, I cannot run this utility because the computer will not boot, it cycles very quickly every three to five seconds with no output on the display.

    singemagique already posted the best suggestion to try regarding your psu.
    Remove the psu from your system as well as the one fan you've mentioned.
    Do this.
    http://www.youtube.com/watch?v=5FWXgQSokF4
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