PC Powers on for 1 Second then turns off?


back in 2007 i purchased a pre-built Overclocked system from Overclockers.co.uk. Up until now everything has been fine, a month ago i replaced the 8800GTX for a ATI 6850 as the older card had fried. A few weeks ago i started noticing that upon start up i would have to press the power button several times before the PC would boot into windows. Now the Computer only powers on for one second, the fans start the MB light and voltage reading displays 9.9 then 8.2 when it switches off, and then the PC shuts down. I have diagnosed all of the hardware components which all pass without faults, and the PSU fan is spinning. So i'm stuck as to what the problem is, could it be the actual power button? does the Motherboard require a constant power source, or only enough to get the system running. I'm unsure and any help would be very appreciated. :)

my System spec is:

Intel Core 2 Quad Q6600 GO 2.40GHz Quad Core CPU Overclocked too a minimum of 3.30GHz and beyond. (8/9 x 400MHz - 1600MHz FSB)
- Tuniq Tower 120 Pro Blue LED Intel approved cooler
- Arctic Silver 5 Heatsink compound professionally hand installed by our technicians
- Abit IP35-Pro Intel P35 (Socket LGA775) PCI-Express DDR2 Motherboard
- Award winning Crucial 2GB Ballistix Tracer PC2-8500 CAS5 (2x1GB) Dual Channel Kit (Overclocked at 1000MHz+) (Note when upgrading to 4GB overclock drops to 3.25GHz on CPU)
- 500GB Western Digital 16MB Cache SATA-2 Hard Drive
- ATI 6850 1GB
- Pioneer 112DBK 18x DVD±RW Dual Layer ReWriter (Black)
- Antec NINE HUNDRED Gamers ATX Case
- OCZ 1010W Next Generation Power Supply
8 answers Last reply
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  1. When you say the voltage reading is 9.9 and goes to 8.2 are you refering to the 12V line on your power supply? Based on what's happening I was leaning toward your psu dying but that voltage reading confuses me as well. Do you have a spare psu to see if your computer will boot fine with it?
  2. Hi, thanks for your reply.i tried the PSU on another system and the PC booted fine, however the other system was lower spec, the reading on the Motherboard is now 8.7 when i disconnect the ATX cables "CPU1" and "CPU2" the computer boots fine, so is this a CPU issue, or is the PSU faulty and not supplying enough power to all of the components. Many thanks
  3. Ok so the psu works fine in another computer and when you put it back into the computer causing issues you are able to boot if you disconnect the power going to your cpu? Can you describe this "ATX cables 'CPU1' and 'CPU2'" as in are you refering to the 4/8pin cpu cable you plug into the motherboard that feeds power to the cpu? I don't think that's what you mean as you can't boot without power to the cpu so I'm lost in your statement.
  4. Hey, yeah they are two separate cables 4/8 pin CPU cable, providing power to the CPU as you have said. The computer runs when these cables are unplugged, when they are plugged in the computer runs for a second then completely switches off. They are definitely the CPU power cables, its quite strange
  5. You have a power supply problem or a direct short. PSU's supply 12, 5, 3.3 volts not 8-9.
  6. I need to show a picture of my head exploding. You are able to post and log into windows if you don't have your cpu power plugged in?
  7. The problem is most likely that the PSU took down your old video card when it effectively died and you just weren't notified by the PSU that it was going down the drain too.

    I am going to hazard a guess that if the PSU hadn't died then your video card wouldn't have died either.

    I think if you get a newer better PSU then everything will come right back to life.

    Beg, borrow, or steal (I mean buy) a new PSU you can shove in there to test this.
  8. Hi,

    its taken a while, however the issue is now solved!! i bought a new OCZ 750W PSU to replace my damaged one and everything is running great! Thanks for the help, turns out it was a faulty PSU..
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