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Brand new custom built PC shuts itself off after powering up for 4-5 seconds

Build a PC
By realms18
Jan 31, 2009
  1. Just built a new computer...
    ASUS m3n72-D mobo
    AMD 9950 2.6 Quad Core
    4 GB Corsair RAIM
    EVGA GTX 260 graphics card
    NZXT Ultimate Cooling Chassis
    Took a 120 GB harddrive out of my old computer (a gateway)

    It ran like a champ for approximately 2 weeks. Now it will not power up at all when I press the power button. When I unplug the PSU or flip the off switch on the PSU, and then plug it back it, the computer immediately begins to try to power up (without me even pressing the power button!). It will begin to power up for about 5 seconds (lights up, CPU fan starts, case fans start, monitor lights up, etc) but then will immediately shut itself off. At first I thought it might be the power button/cord on the chassis, and I fiddled with the connections on that, and then I pressed the power button and it began to start. Again however, it shut itself down after a couple seconds. After the first time messing with the power button connection, the power button will not do anything ever. The computer still attempts to start itself after being unplugged and plugged back in, but always dies.
  2. LinkedKube

    LinkedKube TechSpot Project Baby Posts: 4,268   +42

    Do two things, updated your specs in your profile and lookin in your case, tell us what psu you have.
  3. realms18

    realms18 TS Rookie Topic Starter

    I am using a 700w FSP Epsilon PSU...
  4. kimsland

    kimsland Ex-TechSpotter Posts: 18,353

    Try removing 2 of the gigs of Ram (back to 2Gig only)
    Also you could try disconnecting internals (Case Fan; HardDrive; DVD Drive etc)
    And check all data cables are secure (well ideally test with everything internally diconnected)
    I wrote a guide saying the same as above here: Tutorial: No POST (Power On Self Test)
  5. k.jacko

    k.jacko TS Rookie Posts: 743

    sounds like a psu issue to me, seeing as unplugging it then plugging it back in seems to work.
    Could it be capacitance bleeding off thus allowing it to reboot? (similar to power cycling)
    I'd probably still follow Kims guide though to eliminate everything else.
  6. realms18

    realms18 TS Rookie Topic Starter

    Unplugging and then plugging it back in actually does not work. Doing so causes the computer to START to power up, but it stops within seconds and remains a dead PC
  7. kimsland

    kimsland Ex-TechSpotter Posts: 18,353

  8. realms18

    realms18 TS Rookie Topic Starter

    Tried the 2 Gig dice.
  9. realms18

    realms18 TS Rookie Topic Starter

    I think it's very unusual how plugging in the PSU immediately begins to power up the computer, without me doing anything to start it...could that be an indicator that my PSU is the problem?
  10. k.jacko

    k.jacko TS Rookie Posts: 743

    It could also indicate a faulty case PWRSW connector. I had this once. Luckily i had a spare case which i positioned next to the pc, hooked up the case connector to the mobo and tested it and it worked without cutting out etc. So i swapped the case out and all was fine.
  11. realms18

    realms18 TS Rookie Topic Starter

    Ok...pulled out everything except CPU, heatsink and fan, and the motherboard....still same results. Switch PSU off and then on, the computer attempts to start itself without pushing power button, but shuts itself down after 4-5 seconds....I took off my upgraded heatsink and fan, reseated CPU, applied new thermal paste, and installed the stock AMD heatsink/fan, with no luck either. Had my buddy reset CMOS jumper or whatever that thing is, no luck either.

    Alright, I think I may have found the problem...when I ordered the CPU from website, it recommended a nicer, more expensive heatsink/fan--a Thermaltake Venus 12. When I went back and looked at the paperwork, it claimed that the Venus twelve is compatible with AMD Opteron and 64, NOT the Phenom I was running. I am assuming that the heatsink/fan was not up to the job and my processor fried. Odd though, because I checked the temp in BIOS after installation and it said it was running quite cool.
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