A7N8X Starts then Stops Immediately

Discussion in 'Asus' started by Kappy, Jun 23, 2004.

  1. Kappy

    Kappy Guest

    Problem: Newly installed motherboard. Never used. I push power button,
    system starts to run for 2 to 5 seconds, then shuts down. Everytime.

    This is an upgrade to an A7N8X with Athlon XP2800+ cpu and it has not
    yet worked. I believe that I have installed everything correctly. The
    memory is brand new KBYTE 512 2700. I have swapped power supplies and
    memory with another computer. I have tried booting without the hard
    drive attached, without the video card installed and with all other
    cards installed and removed. I even swapped power switches. The video
    card is a 2001 model year card by Vision Tek. I don't know the voltage,
    but the red light on the motherboard is not lighting up to indicate a
    problem. The power supply is rated at 250w.

    I have not yet tried removing the cmos battery.

    What could be causing this?


    Kappy, Jun 23, 2004
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  2. Kappy

    Blaedmon Guest

    Could be the motherboard shorting on the case - something as simple as that,
    but it sounds vague also. You could, for the benefit of elimination, try
    removing the board and powering it up flat on a table, etc.
    Blaedmon, Jun 24, 2004
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  3. Kappy

    Paul Guest

    Overheat or BIOS isn't detecting tachometer pulses on the
    CPU fan ? The heatsink contact patch should be centered over
    the CPU (a 180 degree rotation of the heatsink might not give
    the right result). There should be a thermal pad or thermal
    paste (not just a dry heatsink) to enhance contact between the
    CPU and the heatsink. The CPU fan should have three wires, one of
    which is the tachometer wire. The CPU fan should spin at least
    1800 RPM, because otherwise the BIOS can read such a fan as
    zero RPM.

    If it still isn't working, move the CPU fan cable to one of the
    other fan headers.

    Paul, Jun 24, 2004
  4. Kappy

    Scotter Guest

    I had same exact problem with same MB.
    I ended up replacing every part until I thought maybe it had something to do
    with the wall socket.
    I ran a 3-prong extension cord from a different socket as far on the other
    side of the house as possible and voila! The machine works fine!
    I need to remember to get an electrician out to test the bedroom socket,
    which is the one I was using initially.
    Scotter, Jun 24, 2004
  5. Kappy

    Apollo Guest

    Your psu isn't up to the job, get 300w minimum, by that I mean a good
    quality branded psu.
    Apollo, Jun 24, 2004
  6. Kappy

    rstlne Guest

    Do what BladeMon says first..
    Is this your first ever computer that you have built..
    did you add a Heatsink and Fan unit on top of the processor (yea, I take
    everyone as one so dont get pissy)

    Once you get it on the table as blademon says then look and make sure that
    the heatsink is sitting on the cpu correctly.

    Also after it shuts off (if the fans on the heatsink were spinning) then
    touch them, see if they are warm.. try near the top of the fan ;)

    It SURE SURE SURE sounds to me like thermal protection (fan speed protection
    should be off by default)
    rstlne, Jun 24, 2004
  7. Kappy

    Kappy Guest

    It was Thermal Protection. I switched the heat sink around 180 degrees
    and it started right up. Thank you very much for your insight and help
    Kappy, Jun 24, 2004
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