CPU or BIOS problem

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  • Jane
    Senior Member
    • Aug 2010
    • 188

    #1

    CPU or BIOS problem

    If a computer main board does not start ( no POST) and ALL voltages( coming from PSU are correct) then, I think, the reason can be one of these:

    1.Faulty CPU
    2.Faulty BIOS
    3.Faulty PCB

    Note: By the computer main board I mean a main board itself( no hard disk or similar connected)
    Is there any way how to find out which the reason ,for the failure from those named above, it is?
    What measuring devices should I use and what pins to measure?
  • gilly1984
    Badcaps Veteran
    • Jun 2012
    • 751
    • UK

    #2
    Re: CPU or BIOS problem

    Faulty Ram too.
    Do NOT touch heatsinks when testing for voltages as they may be LIVE!

    Comment

    • Uranium-235
      Comrade Glimmer
      • Aug 2007
      • 5042
      • US

      #3
      Re: CPU or BIOS problem

      could be faulty cmos too. take the battery out and put it back in

      if its integrated video, try an external video card too

      how do you know the voltages from the PSU are correct? are you using one of those PSU readers. Those dont' always work, cause it doesn't put any stress on the PSU, sometimes it takes a certain amount of stress on the PSU for the voltages to become unstable, which is why I always keep a solid working PSU around for testing purposes

      I would try a single stick of different ram first
      Cap Datasheet Depot: http://www.paullinebarger.net/DS/
      ^If you have datasheets not listed PM me

      Comment

      • brethin
        Badcaps Legend
        • Dec 2008
        • 1907
        • USA

        #4
        Re: CPU or BIOS problem

        Originally posted by Jane
        If a computer main board does not start ( no POST) and ALL voltages( coming from PSU are correct) then, I think, the reason can be one of these:

        1.Faulty CPU
        2.Faulty BIOS
        3.Faulty PCB

        Note: By the computer main board I mean a main board itself( no hard disk or similar connected)
        Is there any way how to find out which the reason ,for the failure from those named above, it is?
        What measuring devices should I use and what pins to measure?
        I would say #4 Faulty Mainboard

        Comment

        • severach
          Badcaps Legend
          • Aug 2007
          • 1055
          • USA

          #5
          Re: CPU or BIOS problem

          Some boards will not power on or POST without a CMOS battery. Don't forget incompatible RAM, incompatible CPU, damaged traces.
          sig files are for morons

          Comment

          • larrymoencurly
            Badcaps Veteran
            • Oct 2004
            • 960
            • USA

            #6
            Re: CPU or BIOS problem

            I've seen 2 motherboards that needed the CMOS battery to boot, one an ancient Socket 7, the other a Socket AM2 or 478.

            I've had motherboards knock out their BIOSes, but boot block recovery always let me see something, at least if I used a separate video card, and I could usually recover by flashing from a floppy disk or USB stick. One exception was an MSI motherboard that would not load in the BIOS from the USB stick (the only recovery method it supported) and kept asking for the file that was on the stick. With that one, I had to use SPMPGM2 and flash from the parallel printer port of another computer. MSI offers 3 methods for flashing the BIOS but recommends not using the 2 methods it recommends most.

            Comment

            • ant3202
              Badcaps Veteran
              • Jun 2006
              • 274
              • Singapore

              #7
              Re: CPU or BIOS problem

              check powersupply ......
              one case.... bad psu, low voltage to startup the mainboard

              imo, cpu rarely fails....

              best if you can list out the pc information, like mainboard made, model, cpu, etc.

              Comment

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