GA-990FXA-UD3 Mainboard won't POST

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  • IAmSad2
    New Member
    • Feb 2023
    • 3
    • germany
    #1

    GA-990FXA-UD3 Mainboard won't POST

    Hi.
    Some weeks ago, my beloved 10 years old PC went belly up

    When I press the power button, the video card cooler start spinning, but I hear no POST beep and I see no image on the screen.
    The CPU gets mildly warm, but it might overheat if let running more than a few minutes without radiator, so I let the radiator on it (no fan).
    There is no chip overheating - I "fingered" all of them , I looked also through a cheap thermal camera.
    Not a single LED lights up.

    Power supply
    I measured the power on all pins. It is all fine except the negative 12V rail, which is 11.18V (but this is still well within its 10% margin).
    At least the main board answers to the power button. I can start the computer, and if I keep the power btn pressed for 4 seconds, it also turns off the power supply PC.
    The pin 8 (PowerGood) is +4.1V - I don't know if this is its good value...

    BIOS/CMOS
    Trying to clear CMOS, also nothing. The second BIOS won't kick in.
    I tried to force the backup BIOS chip kick in:
    Keeping the reset and pwr buttons pressed for 10 seconds while turning on the power supply.
    Keeping the power btn pressed to 10 seconds.
    Keeping the power btn pressed while turning on the power supply and then imediatelly shutting it down.
    None worked.

    Any ideas? Any hints?
    Please help a sad guy....

    ______

    The system is (was):
    GA-990FXA-UD3 (rev. 3.0) DualBios https://www.gigabyte.com/Motherboard...upport-dl-bios
    AMD FX-8350 4GHz
    32GB RAM
    PSU Antec 750W
    All capacitors are ok. None seems swollen.
    Tags: None
    • jiroy
      Badcaps Legend
      • Jun 2016
      • 2416
      • Lebanon
      #2
      Re: Mainboard won't POST

      What's left to try ... try different Rams . Try also another VGA if you can , since there's no onboard VGA . Try changing the Bios battery ..
      While booting , keep an eye on keyboards lights , and if they come normal , it would be a signal of a faulty VGA .

        Comment

        • Per Hansson
          Super Moderator
          • Jul 2005
          • 5895
          • Sweden
          #3
          Re: GA-990FXA-UD3 Mainboard won't POST

          Originally posted by IAmSad2
          The pin 8 (PowerGood) is +4.1V - I don't know if this is its good value...
          Power good should be 5v, I checked my own powers supply and it is 4.7v.
          There is some tolerance here but it will be different for every mainboard what it actually accepts...
          Do you have another power supply to test with?
          "The one who says it cannot be done should never interrupt the one who is doing it."

            Comment

            • IAmSad2
              New Member
              • Feb 2023
              • 3
              • germany
              #4
              Re: GA-990FXA-UD3 Mainboard won't POST

              I have old power supplies. Simple ones. Many
              But none for this mainboard. The main board requires separate power supply cable for CPU and video card.

                Comment

                • N²x²N
                  Senior Member
                  • Apr 2023
                  • 54
                  • Italy
                  #5
                  Re: GA-990FXA-UD3 Mainboard won't POST

                  Are cpu, northbridge or southbridge getting hot?

                    Comment

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