TechSpot

PC powers down and up on its own

By Tachyon768
Jun 24, 2008
  1. OK, quick background: I am a software developer and have built perhaps 30 systems in my life, and this is the first time I have every been this baffled. I have come here looking for help! Thank you in advance!

    Last week I woke up and walked over to my 6-month-old dev machine (it has worked flawlessly since Dec 07). It was hibernating. I moved the mouse, then tapped the space bar, but the system didn't respond. I hit the reset button and the system restarted. Here's where the problem is:

    The system comes on, stays up for 4-5 seconds, there are no beeps and it does not post, then it shuts down. It repeats this over and over until I shut the power supply off.

    Now then, before you give any advice, here is what I have done:

    I assumed it was the power supply, so I have replaced it twice. The current PSU is a Antec 850watt unit. I've tried multiple outlets and a different surge protector but the system still does the same thing!

    Then I assumed it was the Motherboard. I first tried a new ATX micro board from a local shop (the system still did the same thing) then I ordered a new MoBo from NewEgg. The system still does the same thing.

    I had the CPU checked out, and it was fine. Still, I bought a new one just to be safe and the system still does the same thing!

    I have replaced the video card with one that I know works (to prove it, I am using it now on this system to post this message). The video card swap did nothing- the system still did the same thing.

    I have not tried new RAM, but I took out all the RAM in hopes that it would post with a memory error, but the system still does the same thing.

    So, basically I am looking at a system with a new motherboard, a new CPU, a new power supply, all connections checked and re-checked a dozen times, with and without RAM, different video cards, hard drives connected but I've since disconnected those SATA cables as well, and still:

    The system comes on, stays up for 4-5 seconds, there are no beeps and it does not post, then it shuts down. It repeats this over and over until I shut the power supply off.

    Please, before I kill myself, can someone tell me what is wrong?

    My current specs (with all the new crap):
    Intel E8500 Core2 Duo CPU
    Gigabyte GA-EP35-DS4 motherboard
    Ballistix PC800 RAM (4 gig)
    MSI nVidia 8800GTX video card
    Antec 850watt PSU
    plus a few hard drives and a DVD drive that are not connected.
     
  2. Tachyon768

    Tachyon768 TS Rookie Topic Starter

    Oh, I wanted to add that I have removed the wires going to the front of the PC (the power switch, reset button and HD LED wires), just to make sure those weren't shorting out. I can of course turn the PC on by touching the Power SW pins with a screwdriver...but of course, the system is still exhibiting the same problems as noted above.
     
  3. boykov

    boykov TS Rookie Posts: 131

    Hi

    Did you ground yourself before handling any of the newly installed parts..?
    Do you have any fans on, other than the CPU fan connected to the board..?

    there is still the possibiliy that the defective part destroyed a new one (even if it the part was plugged once to a new device) ...

    Have you tested any of the unplugged devices on a different machine?

    cheers
     
  4. Tachyon768

    Tachyon768 TS Rookie Topic Starter

    boykov:

    I am still unsure what the problem was, but it is fixed now. I went through 3 different motherboards, all new RAM, and a new CPU before it was fixed. Basically, other than the hard drives and the video card, the system has been gutted and updated.

    Ultimately, it came down to either a series of bad Gigabyte motherboards or faulty Ballistix RAM. I am now running an ASUS nForce motherboard just fine.

    Thank you for taking the time to respond.
     
  5. boykov

    boykov TS Rookie Posts: 131

    You're welcome

    cheers
     
  6. Gflo

    Gflo TS Rookie Posts: 105

    you baisicly replaced your computer and its was still messed up then the answer must be:GREMLINS. nasty boogers get into everything.
     
  7. angryCrayon3

    angryCrayon3 TS Rookie Posts: 29

    i think your PCs possested. jk, good luck
     
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