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System Won't Boot - ATX Power Supply

Discussion in 'PC Hardware' started by JJ, Jul 12, 2005.

  1. JJ

    JJ Guest

    Hi. I got a Socket 478 Northwood ATX motherboard that wouldn't startup
    with the normal Power On Self Test (POST) beep. The system would power
    up where the CPU fan starts, the HDDs spin up, the mobo LED lights up
    and the power supply fans all spin up. But the video would stay blank
    and there is no POST beep!

    I've taken out everything from this system until I only had the video
    card installed and it still wouldn't POST. But it turns out the ATX
    power supply was the culprit. I temporarily replaced this one with
    another ATX power supply and it starts up normally. So I'm out $60 with
    and order to Newegg for a replacement.

    Anybody had this problem before? Its bizarre that everything spins up
    and it turns out to be the power supply preventing proper system boot
    up. That threw me off for a couple of days as I thought maybe the video
    or memory was a problem. :-( I learn something new every time...
    JJ, Jul 12, 2005
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  2. You didn't mention any details on the power supply that wouldn't work
    - new? Wattage? Brand?

    Today's motherboards suck power from the power supply. If you buy the
    cheapest, minimal power supply that you can get, you may have issues.

    Recently I have stayed with Antec 400-450 watt power supplies that
    came with my Antec cases. I prefer PC Power and Cooling "Silencer"
    power supplies -- whenever these fail, I'll probably switch them to
    those from pcpowercooling.com .

    My website: http://www.terrystockdale.com
    My weekly newsletter: http://www.terryscomputertips.com
    Terry Stockdale, Jul 12, 2005
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  3. JJ

    Arno Wagner Guest

    This could happen if the PSU does not assert the "power-good" signal.
    Before this signal is active the mainboard will stay in a reset state,
    since it cannot assume stable voltages from the PSU.

    Arno Wagner, Jul 12, 2005
  4. JJ

    JJ Guest

    Its a 400 watt power supply -- fairly low on the price -- the brand is
    "Skyhawk Steel". Its been working for over two years with this
    motherboard until now! :(

    I ordered a 500 watt power supply as a replacement. I hope this one is
    a higher end one. I like the individually wrapped power cables:

    JJ, Jul 12, 2005
  5. JJ

    JJ Guest

    I think you're right. I've just read about the POWER_GOOD signal in
    Scott Mueller's "Upgrading and Repairing PCs" book. Its bizarre that
    that all the fans and lights are on though. I'll definitely be
    considering the the power supply the next time I encounter a system that
    suddenly stops to boot normally.
    JJ, Jul 13, 2005
  6. mueller (aka saint scott) also writes that a bad power supply can cause
    almost anytrhing. His 16th edittion i got from the library to look for
    new info a few weeks ago, and he wrote that a bad psu can cause a usb
    device to go unrecognised.
    he also discusses a method of testing the PSU voltages with a
    multimeter. Though any electrician says that it doesn't properkly test
    the voltages. I think everything else he says is accurate though. The
    most interesting and striking statement in the 16th edition was a
    ctiticism of spinrite, since spinrite's author 'steve gibson' has been
    venerated to god status.
    jameshanley39, Jul 14, 2005
  7. JJ

    Arno Wagner Guest

    Not really. Fans and lights are non-critical. They will not break if
    the voltages are too low or unstable. CPUs, e.g., are a different
    matter. So the fans are often just connected directly and will start
    when the PSU delivers enough power.
    It is a major source of problems in PCs, especially the cheaper ones.

    Arno Wagner, Jul 14, 2005
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