Computer turning on and off repeatedly


been having trouble with my PC recently, i'll start off with the specs:

Asus P5K-E
OCZ StealthXtreme
Nvidia GTX260

It started a few days ago when i tried to power on the computer it would turn on and off a few times then eventually it would stay on and act as normal until the next day i tried turning it on. Eventually i decided to open up the case and look to find if the motherboard was shorting on the case, i couldnt find any indication. I cleaned the case out of dust etc then tried powering it on. It wouldnt boot at all and just kept cycling on and off until i had to turn it off by the surge protector.

At this stage i knew i couldnt put it off and had to remove everything from the case to investigate any shorting from the case. Eventually after removing all the components i placed the motherboard outside of the case and tried powering on. It still wouldnt power on properly so i imagine this ruled out problems with the motherboard short circuit. I was really out of ideas now.

I should also point out when trying to power on the cpu fan would spin but the PSU fan would NOT even attempt to spin whatsoever.

I read online that taking out the mobo battery/moving jumpers may solve the problem but i didnt have any luck with this. Saying that, i followed the time of 20-30 seconds of having the battery removed as described in the mobo manual however some people have had it removed for 2-3 hours, I may have to try this. I ordered a PSU today which should hopefully come tomorrow (wed), so i can test the PSU then. I'm hoping it fixes it because i'm really clueless as what the problem could be.

If anyone has any ideas i'd appreciate it.
6 answers Last reply
More about computer turning repeatedly
  1. Is it overclocked at all? If it is set the bios to optimized settings and see if that helps.
    I dont know about the PSU it could be going bad, or the fan never had time to turn on but I dont know. Do you have another one laying around, if so try it.
  2. Oh what size PSU
  3. size? standard ATX size PSU i guess. If you mean watts? then 600w.

    I can't get into BIOS but i've tried resetting the jumpers etc but it didnt make a difference.
  4. Do you have another cmos battery? Sometimes when they go the computer wont boot.
  5. One problem that can cause your symptom is inadequate cpu power, for example, leaving the 4/8-pin connector unplugged. This could also be caused by a failing/failed psu.

    There are several ways to clear CMOS - this combines all of them:

    Pull plug from wall, turn off PSU switch, remove battery, press "Clear CMOS" button several times if equipped, press case Power Button 10 times, go grab a cup of coffee.

    When you come back, CMOS is clear.
  6. Just wanted to say that I had the same symptoms as the OP, I would press the power button and the fans would run for like 2 seconds, then shut down, the run for 2 seconds, shutdown, etc. I took off the battery for a couple minuts and it solved my problem. If your computer doesn't power on, make sure your POWER SW pins from the front panel are in the right pins... I know it's stupid but I actually replugged them in the wrong ones and wondered for like 2 hours why my computer wouldn't turn on!
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