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Abit AI7 mosfet overheating

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    Abit AI7 mosfet overheating

    A few days ago I found this wonder of the motherboard, it turns out that it had 2 rubycon in bad condition, and I realized that around the mosfet it is darker, as if it has overheated, damaging the capacitors, when I turn it on you start to heat, is this normal?
    The transistor reduces from 5v to 3.3v for circuits that work at 3.3v, and I don't see anything unusual.
    The transistor marked in yellow is the one that overheats.
    Attached Files
    Gaming pc:
    nVidia RTX 3080 TI, Corsair RM750I.
    Workshop PC:
    Intel core i5 8400, Intel SSD 256GB, nvidia gt1030, asus b365-a.
    Server:

    #2
    Re: Abit AI7 mosfet overheating

    have u replaced the bad caps yet? its still overheating even after the caps are replaced? im asking because mosfets dont overheat by themselves. a few scenarios could have occured to cause this fault.

    first, a high power video card could have been used and ran hot, overheating the caps and making them fail. consequently, the mosfet has to increase its duty cycle to keep up with the failing caps until it overheated.

    unclean power from the psu's 5v rail could have also caused too much ripple and cause the caps to bloat. a power surge could also have dmged the lan chip, southbridge chip or some other chip causing them to become shorted and draw too much power hence the mosfet overheats because too much power is being drawn from something shorted on the board.

    so that is definitely not normal. yes, nice wonderful board too btw. 865pe chipset with the atx 12v connector by the side of the board instead of the center of the board like so many 865pe boards out there. looks almost as good as an 875p board. i would hope to get it working too.

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      #3
      Re: Abit AI7 mosfet overheating

      Originally posted by ChaosLegionnaire View Post
      have u replaced the bad caps yet? its still overheating even after the caps are replaced? im asking because mosfets dont overheat by themselves. a few scenarios could have occured to cause this fault.

      first, a high power video card could have been used and ran hot, overheating the caps and making them fail. consequently, the mosfet has to increase its duty cycle to keep up with the failing caps until it overheated.

      unclean power from the psu's 5v rail could have also caused too much ripple and cause the caps to bloat. a power surge could also have dmged the lan chip, southbridge chip or some other chip causing them to become shorted and draw too much power hence the mosfet overheats because too much power is being drawn from something shorted on the board.

      so that is definitely not normal. yes, nice wonderful board too btw. 865pe chipset with the atx 12v connector by the side of the board instead of the center of the board like so many 865pe boards out there. looks almost as good as an 875p board. i would hope to get it working too.
      Yes, I replaced the capacitors and it overheats the same, and overheats with any graphics card, even without a card it overheats the same, what surprises me is that the resistance of the 3.3v track is the same as that of an asrock motherboard with the same chipset.
      What I'm going to do is replace the mosfet, and I'll put a heatsink on it to keep it cool.
      The motherboard itself turns on and displays the BIOS smoothly, only the mosfet overheats.
      The truth is that this motherboard is very beautiful, for my Abit they were one of the best motherboard manufacturers, that's why I am restoring this motherboard, the Abit motherboards are disappearing, this AI7 was taken from a tower that was in a container , it was missing the heatsink of the chipset And I put the one of an Asrock, I checked the board in case something was missing and there was nothing strange, there were only those 2 capacitors that I replaced with a rubycon and a nippon chemicon.

      Offtopic, I also have an Abit kn9 ultra and it is also very cool, and the silent otes heatsink is amazing, I have it with an AMD X2 3600 and nVidia 8500 (It still works, install a fan and increase the life of the FCBGA ), and I am impressed by the great performance it offers, all the games of its time move them very well, and the ram memory has a performance of almost 8GB / s at 800 MHz, this motherboard is wonderful.
      Gaming pc:
      nVidia RTX 3080 TI, Corsair RM750I.
      Workshop PC:
      Intel core i5 8400, Intel SSD 256GB, nvidia gt1030, asus b365-a.
      Server:

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