PSU requirements for FIC AU31 or K7MNF-64?

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  • gdement
    Badcaps Veteran
    • Jan 2007
    • 690

    #1

    PSU requirements for FIC AU31 or K7MNF-64?

    Short version:
    I'm looking for the original PSU ratings for each voltage rail, cross load limitations etc for the power supplies that were originally used with the FIC AU31. I know that board was killed by lots of infamous Bestec eMachines computers, so I bet there's lots of people here who might have those PSUs around.

    I need a power supply for a very similar board (FIC K7MNF-64) so knowing those amperage values would help identify a good replacement.
    ==============

    Long version:
    I recently bought an FIC K7MNF-64 motherboard. This board is very similar to the AU31, in fact the person selling it was advertising it as a replacement for Gateway/HP/etc machines that originally had the AU31 in them.

    In my case, I'm using it for a low-budget fix/hotrod of an old MicroATX P3 Dell, and obviously have to replace that power supply (proprietary pinout).
    I intended to use an FSP 300W power supply, same as one I use on a full size nForce2 ABit AN7 board. It powers a fully loaded AN7 perfectly, but to my surprise it's slipping against the K7MNF-64.

    With just a single 512MB module installed, at 166FSB, and a mobile Thoroughbred that's probably running underclocked, I'm getting these voltages in the bios:

    Vcore 1.58
    3.3 3.32
    5 5.02
    12 11.58

    Everything's fine except the 12v rail. Technically 11.4v is legal but I don't want it this low. It's only going to get worse when I add load to it.

    I do have some AcBel 550W psus that have been discussed in this forum before. They're great for newer boards but last time I tried to use one on my AN7 I ruined the 3.3v supply in about 1 week. The 3.3+5v rating on those AcBels is pretty modest. Maybe it's fine though - I don't know what this board needs. I'd feel better about using the AcBel if I could compare values from the OEM psu for an AU31 (which I don't have).

    I looked up the psu from a representative AU31-based emachine, and came up with these part numbers:
    eMachines p/n: 100929 (300W psu)
    SKU: PWEM100929A3

    Can't find anything online that tells the amperage ratings for each rail, or the combined 3.3+5v wattage limit.

    I may just throw an AcBel at it and hope for the best, but if somebody has the ratings from an AU31 psu it would be much appreciated.
  • PCBONEZ
    Grumpy Old Fart
    • Aug 2005
    • 10661
    • USA

    #2
    Re: PSU requirements for FIC AU31 or K7MNF-64?

    Add a hard drive or two and see what +12v does.
    It may not be loaded ENOUGH to regulate properly.
    Mann-Made Global Warming.
    - We should be more concerned about the Intellectual Climate.

    -
    Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

    - Dr Seuss
    -
    You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
    -

    Comment

    • gdement
      Badcaps Veteran
      • Jan 2007
      • 690

      #3
      Re: PSU requirements for FIC AU31 or K7MNF-64?

      Turns out I was mistaken, it actually had power connected on a hard disk and cdrom. They just weren't hooked up to the board.

      The previous processor was running at 1000/166. Swapped it to a palomino 1400/133, supply voltages are still exactly the same.
      It seems to work fine in memtest86 and booted knoppix okay. The 12v reading is consistent but I don't like it.

      Comment

      • gdement
        Badcaps Veteran
        • Jan 2007
        • 690

        #4
        Re: PSU requirements for FIC AU31 or K7MNF-64?

        Testing with 1gb ram and a ti4200 video card still gets the same 11.58v reading. It's like the board just wants it there.
        5v dropped a negligible amount, that's all.

        I think I'll try the AcBel though. When I burned out the other one it was with a ti4200 that I think guzzles 3.3v. Just using onboard video with this machine.

        Comment

        • gdement
          Badcaps Veteran
          • Jan 2007
          • 690

          #5
          Re: PSU requirements for FIC AU31 or K7MNF-64?

          Hooked up an AcBel, now everything is slightly low but well within spec.

          3.3 3.26
          5v 4.91-4.94
          12v 11.84-11.90

          I'll check it again after it logs some miles and see if anything is slipping.
          Conveniently, the 20 and 4pin connectors on this board are properly positioned to fit a 24/8pin PSU. I really like the connectors on this board, everything fits without modification, even the Dell front panel connector (actually an Intel spec pinout).


          If anybody knows the amperage values from an AU31 eMachine that would still be great to know for comparison purposes. Thanks.

          Comment

          • 370forlife
            Large Marge
            • Aug 2008
            • 3112
            • United States

            #6
            Re: PSU requirements for FIC AU31 or K7MNF-64?

            Wait, you are looking at these in the bios...

            (Bonez...pay attention!!)

            Use a Digital Multimeter, the bios (and any software...) is almost always inaccurate.

            Comment

            • PCBONEZ
              Grumpy Old Fart
              • Aug 2005
              • 10661
              • USA

              #7
              Re: PSU requirements for FIC AU31 or K7MNF-64?

              Pay attention to what?
              As I recall gdement uses [or knows how to] a scope.
              Pretty sure he knows when to confirm with a DMM.
              Mann-Made Global Warming.
              - We should be more concerned about the Intellectual Climate.

              -
              Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

              - Dr Seuss
              -
              You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
              -

              Comment

              • 370forlife
                Large Marge
                • Aug 2008
                • 3112
                • United States

                #8
                Re: PSU requirements for FIC AU31 or K7MNF-64?

                Originally posted by gdement
                With just a single 512MB module installed, at 166FSB, and a mobile Thoroughbred that's probably running underclocked, I'm getting these voltages in the bios:

                Vcore 1.58
                3.3 3.32
                5 5.02
                12 11.58
                Didn't say anything about using a DMM.

                Comment

                • gdement
                  Badcaps Veteran
                  • Jan 2007
                  • 690

                  #9
                  Re: PSU requirements for FIC AU31 or K7MNF-64?

                  I don't think the low 12V reading was false since it went up when I swapped PSUs. I've never seen BIOS readings disagree with multimeter, but it won't hurt to check that anyway.

                  If the readings hold as they are with the AcBel then it's no problem. My only worry is whether the AcBel's 3.3 or 5v rails are underrated for this board, because I had the 3.3v die on another board once. But no slipping so far after memtesting overnight.

                  As I recall gdement uses [or knows how to] a scope.
                  No scope here.

                  Comment

                  • eagle3
                    New Member
                    • Sep 2009
                    • 1

                    #10
                    Re: PSU requirements for FIC AU31 or K7MNF-64?

                    It's an nForce2 board and uses principally the +12v rail,

                    Amperage requirements will depend on hardware installed, particularly graphics card.
                    Something like
                    +12V - 20A
                    +5V - 30A
                    +3.3V - 30A
                    should suffice in most cases.

                    Comment

                    • kc8adu
                      Super Moderator
                      • Nov 2003
                      • 8832
                      • U.S.A!

                      #11
                      Re: PSU requirements for FIC AU31 or K7MNF-64?

                      iirc the fic au31 emachines board runs the vcore vrm from +5

                      Comment

                      • gdement
                        Badcaps Veteran
                        • Jan 2007
                        • 690

                        #12
                        Re: PSU requirements for FIC AU31 or K7MNF-64?

                        I gave it back to the owner, seems to be running fine so far.

                        Comment

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