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Dead Gibabyte mobo!!!

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    #1

    Dead Gibabyte mobo!!!

    Hi guys
    I bought a Ga-p55-us3l from ebay and i have a weird problem as far as i can tell.
    When i plug the atx24 pins connector along with the 12V 4 pins atx connector, the motherboard doesn't show any sign of life( phase led light off ) cpu and gpu fans are off and of course no post or whatsoever.
    When i disconnect the atx12v connector ,the cpu fan starts to turn and the CPU phase lights come on.
    I have a good electronics background, but i've never tried to fix a mobo before!!
    I want to do some troubleshooting, but i don't have any schematic and i don't know where to start from!
    can someone help me please!!!
    Tags: None
    #2
    Re: Dead Gibabyte mobo!!!

    as this connector is for added CPU power, check this line for short

    Comment

      #3
      Re: Dead Gibabyte mobo!!!

      Shorted MOSFET on CPU VCore VRM. Measure exact resistance between +12V and ground inside this P4 CPU power connector (+12V is the pins that connect to yellow wire, ground is the pins that connect to black wire), with the power supply cable actually disconnected.
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

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        #4
        Re: Dead Gibabyte mobo!!!

        Originally posted by piernov View Post
        Shorted MOSFET on CPU VCore VRM. Measure exact resistance between +12V and ground inside this P4 CPU power connector (+12V is the pins that connect to yellow wire, ground is the pins that connect to black wire), with the power supply cable actually disconnected.
        Thank you guys for your inputs
        I have a short between the 12V rail and ground inside the connector!
        i have found some shorted source and drain on some Mosfet's ( K4212)
        I guess this Mobo is not worth fixing!!!
        I only want what could went wrong!!could be a bad Power supply unit, because i have tried this board with a cheap Power supply and since then i ended up having this problem and two defective CPU's?

        Comment

          #5
          Re: Dead Gibabyte mobo!!!

          it's just mosfet/s, replace check caps and it will be good to go

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            #6
            Re: Dead Gibabyte mobo!!!

            yes, this type of repairs last long
            Im Back... sort of...

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              #7
              Re: Dead Gibabyte mobo!!!

              i'll check if i can find some good deal on these Mosfet's on ebay or aliexpress!!!
              thank you guys for your inputs
              best regards

              Comment

                #8
                Re: Dead Gibabyte mobo!!!

                mosfets is mosfets. u can keep it from another mobo or gpu.

                Comment

                  #9
                  Re: Dead Gibabyte mobo!!!

                  I don't have the same point of view there… CPU VCore MOSFETs are quite sensitive in my experience. Only replacing the shorted one with random MOSFET from Aliexpress always resulted in the board dying again.
                  For piece of mind I replace all the high-side (or low-side) MOSFETs with ones from the same batch, avoiding Chinese eBay seller or Aliexpress. I also replace the PWM controller for the MOSFET that died, or if everything is integrated into the CPU buck controller itself I replace it as well.
                  OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

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                    #10
                    Re: Dead Gibabyte mobo!!!

                    im not replacing for random from aliexpress. im mostly using used genuine from used mobo and mostly with higher walues

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