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Asrock 939Dual-SATA2

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    #1

    Asrock 939Dual-SATA2

    Hello,

    This board is currently running fine, with some rare instants when it does not POST at the first time when powered up (it keeps restarting until it succeeds, usually 2-3 times) or it does not POST at all and I have to power cycle the computer. However, I would like to give a try at recapping it, because I don't intend to change my computer very soon. The same board was discussed by user gonzo0815 quite a while ago here. I just want to make sure that I won't do anything stupid, so here I am, asking the pros.

    The capacitors that are in the line for replacing are some UCC KZG 3300uF/6.3V, which already failed me on another board as shown in this thread (I want to put some Panasonic FMs instead), LTec LZP 1000uF/6.3V (-> Panasonic FM) and OST RMH 100uF/16V (-> Nichicon PW).

    The UCC KZEs around the CPU and memory slots and two UCC KMG next to the PCIe slot (which I don't use anyway) should be fine and will not be replaced.

    One last question is about the CPU fan header, which has an empty capacitor place next to it. Should a filter capacitor go here, and if yes, what value?

    Thanks a lot!

    Dan
    Tags: None
    #2
    Re: Asrock 939Dual-SATA2

    Originally posted by amartolos View Post
    the CPU fan header, which has an empty capacitor place next to it. Should a filter capacitor go here, and if yes, what value?
    I've seen 47uF, 25V on some mobos, but other mobos use a ceramic cap, which on some Gigabyte mobo schematics is 0.1uf, 25V.

    Comment

      #3
      Re: Asrock 939Dual-SATA2

      Finally, managed to recap it. I can say that it is a robust mainboard, as it took a fair amount of damage during desoldering , but it survived. I used the opportunity to lap the NB and SB heatsinks, as well as the CPU heatspreader and the cooler, but unfortunately with no obvious change in idle/load temps.
      Oh well, here is the replacement list:

      OST RMH 100uF/16V, positions 6,7,17,18,30,71,72,73,83,84,85 - replaced with Nichicon VZ

      LTec LZP 1000uF/6.3V, positions 8,9,11,12,14,16,34,40,41,42,43,44,52,53,54,64,76,80,81,82,83,89,90,91,93 - replaced with Nichicon HM (whew, this was a long list)

      UCC KZG 3300V/6.3V, positions 21,22,24,25,26,27 - replaced with Rubycon MBZ

      After recapping the sound card output seems to be cleaner (before, moving windows on the screen caused some annoying buzzing). Also, when the system is put to full load (like starting prime95) the speed of the fans remains now constant (it was obviously decreasing, probably due to poor voltage regulation).

      Ah, yes, and...

      Originally posted by Th3_uN1Qu3
      RoHS sucks.

      Comment

        #4
        Re: Asrock 939Dual-SATA2

        Make sure you have the appropriate cool'n quiet drivers loaded from AMD's website and Windows XP set to "minimal power management". Took me a minute to figure out how to get it to work, but once that combo has been enabled the CPU clock speed should throttle down when idle.

        Comment

          #5
          Re: Asrock 939Dual-SATA2

          Originally posted by amartolos View Post
          One last question is about the CPU fan header, which has an empty capacitor place next to it. Should a filter capacitor go here, and if yes, what value?Dan
          That cap keeps the electrical noise from the fan's motor from getting into the power distribution on the board.
          I've seen everything from 22uF to 120uF used.
          33uF, 47uF, and 100uF are probably most common.
          Go for the middle and use a 47uF unless you have none and a 33 or 100 uF is at hand.
          A 16v cap is good enough [is on 12v] as long as it's not a crap brand.
          .
          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.
          -

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            #6
            Re: Asrock 939Dual-SATA2

            Since I had one on the bench I looked at a C2D Intel board.
            It has a 100uF 16v there.
            .
            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

              #7
              Re: Asrock 939Dual-SATA2

              Wait, after I inspected more closely, I think a SMD ceramic cap should go in there. Actually, some pictures would be useful here. Maybe I can try and make some nice ones.

              Make sure you have the appropriate cool'n quiet drivers loaded from AMD's website and Windows XP set to "minimal power management".
              Sorry for my bad english, what I wanted to say was that improving the surface finish did not bring anything. CPU throttling works well, it slows from 2200 MHz to 1000 when idle, and also Vcore drops. Idle temp is ~30 °C and it goes to ~57 °C at full load (Opteron 175 CPU). At idle, one of the cores is 3-4 °C warmer than the other, but they are at the same temperature under load. On the other hand, the cooler is probably not the best. Anyway, the south-bridge heatsink was really warped, there was obviously some free space beneath the center. I have made it flatter now.

              Comment

                #8
                Re: Asrock 939Dual-SATA2

                Originally posted by amartolos View Post
                Wait, after I inspected more closely, I think a SMD ceramic cap should go in there. Actually, some pictures would be useful here. Maybe I can try and make some nice ones.



                Sorry for my bad english, what I wanted to say was that improving the surface finish did not bring anything. CPU throttling works well, it slows from 2200 MHz to 1000 when idle, and also Vcore drops. Idle temp is ~30 °C and it goes to ~57 °C at full load (Opteron 175 CPU). At idle, one of the cores is 3-4 °C warmer than the other, but they are at the same temperature under load. On the other hand, the cooler is probably not the best. Anyway, the south-bridge heatsink was really warped, there was obviously some free space beneath the center. I have made it flatter now.
                Temps sound normal to me. If the board runs stable I say leave it alone and enjoy it till it finally dies.

                Comment

                  #9
                  Re: Asrock 939Dual-SATA2

                  Temps sound normal to me.
                  Yep, I'm still running an Opteron 165 on a 939Dual board, and with the stock AMD cooler I get about 34C idle and 55C under load, with 3-4C difference between the cores. As long as the CPU stays under about 60C or so, you have nothing to worry about.

                  Comment

                    #10
                    Re: Asrock 939Dual-SATA2

                    Concerning the fan headers and their capacitors, here are the promised pictures. I have also made pictures of the other Asrock board I have (K7VT4A Pro). I think the picture with the location of the northbridge fan shows best that a SMD cap should go to C152.

                    I am now wondering: is the 12V present at the fan header the same as 12V from the PSU, or it has gone through some filtering? And where would it be best to connect a fan, from the point of view of generated electrical noise?
                    Attached Files
                    Last edited by amartolos; 11-04-2011, 01:35 PM. Reason: forgot attachments

                    Comment

                      #11
                      Re: Asrock 939Dual-SATA2

                      One more comment: I would really put a fan to cool the northbridge area. gonzo0815 in his thread mentioned that the three capacitors there get very hot during the operation. There are also some power FETs soldered to the board, and on the backside one can already see a change in colour.
                      Attached Files

                      Comment

                        #12
                        Re: Asrock 939Dual-SATA2

                        The +12v for fans comes from the 20 or 24 pin main power connector.

                        The +12v for CPU[s] comes from the auxiliary +12v connector.
                        On that board it's the usual/typical 2x2 [4-pin].
                        Servers and some higher end boards [needing more CPU power] might have more pins, more connectors or both for CPU power.

                        On some boards the two +12v supplies are connected together through the board.
                        [That's the usual case on older boards.]
                        On other boards they are completely separate.
                        [That's the usual case from about the time PSUs started having multiple +12v rails.]
                        .
                        Last edited by PCBONEZ; 11-04-2011, 07:25 PM.
                        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

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