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Asus A7V8X-X recap

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    #1

    Asus A7V8X-X recap

    Hi guys,
    This is my first thread and great forum btw. I like messing around with old school hardware. The board has nippon chemi con KZE 1500uf 6.3v as primary cpu filtration and crappy OST 1500uf 6.3v close to the cpu. I've pulled some nichicon 820uf 2.5v polymer caps from a dead 360. Can i replace OST caps with nichicon poly ones (tested with ESR meter)?
    Last edited by nick122; 07-17-2016, 05:58 AM.
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    #2
    Re: Asus A7V8X-X recap

    i dont really recommend poly modding those boards from the pentium 3 and athlon xp era or older as those boards were before the time of ultra-low esr caps. the vrm may not like the ultra low esr of the poly caps.

    also the vrm only uses 2 power phases. this means that if the output capacitance is reduced, it can produce inexplicable freezing or other kinds of weird behaviour.

    suitable japcap replacements would be rubycon ZLH, ZL; panasonic FM, FR; nichicon HD.
    Last edited by ChaosLegionnaire; 07-17-2016, 04:49 PM.

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      #3
      Re: Asus A7V8X-X recap

      Thanks for reply. I'll order some nichicon HDs online and post pics after modding.

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        #4
        Re: Asus A7V8X-X recap

        ooops i forgot to mention that since u are into good ol' stuff like me, u'd want the longest lasting endurance rating lifetime caps so the board lasts u as long as possible. panasonic FR would be the longest lasting rated cap of choice. sorry if u already paid for the nichicon HDs...

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          #5
          Re: Asus A7V8X-X recap

          Originally posted by ChaosLegionnaire View Post
          i dont really recommend poly modding those boards from the pentium 3 and athlon xp era or older as those boards were before the time of ultra-low esr caps. the vrm may not like the ultra low esr of the poly caps.

          also the vrm only uses 2 power phases. this means that if the output capacitance is reduced, it can produce inexplicable freezing or other kinds of weird behaviour.

          suitable japcap replacements would be rubycon ZLH, ZL; panasonic FM, FR; nichicon HD.
          IIRC, A7V8X comes stock with Nichicon HD in the VRM high and Nichicon HM in the VRM low...

          You might be able to get away with HD in the VRM low.
          "We have offered them (the Arabs) a sensible way for so many years. But no, they wanted to fight. Fine! We gave them technology, the latest, the kind even Vietnam didn't have. They had double superiority in tanks and aircraft, triple in artillery, and in air defense and anti-tank weapons they had absolute supremacy. And what? Once again they were beaten. Once again they scrammed [sic]. Once again they screamed for us to come save them. Sadat woke me up in the middle of the night twice over the phone, 'Save me!' He demanded to send Soviet troops, and immediately! No! We are not going to fight for them."

          -Leonid Brezhnev (On the Yom Kippur War)

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            #6
            Re: Asus A7V8X-X recap

            Originally posted by nick122 View Post
            The board has nippon chemi con KZE 1500uf 6.3v as primary cpu filtration and crappy OST 1500uf 6.3v close to the cpu. I've pulled some nichicon 820uf 2.5v polymer caps from a dead 360. Can i replace OST caps with nichicon poly ones (tested with ESR meter)?
            Probably yes.

            Technically speaking, ChaosLegionnaire is correct in saying that is it not always a good idea to reduce the capacitance on old Pentium 3 / AMD Athlon motherboards...

            *However*, there is a more scientific way to check if you can poly-mod an old motherboard. You do this by looking at the output toroids/inductors next to the CPU socket. If they have only a few turns of wire (multiple strands tied together counts as one thick wire), then the CPU voltage regulator (VRM) probably switches at relatively high frequency, and poly-modding the board (and hence dropping the capacitance a bit) should be possible. But if the inductors have only a single strand of wire or two and there are many turns (typically 10 or more), then the CPU VRM probably switches at relatively low frequency, and poly-modding *may not* give you a stable motherboard. Also, be especially careful on old motherboards if you see a DBL494 / TL494 or KA7500 PWM controller close to the CPU. Those controllers typically indicate that you may be dealing with a very old CPU regulator design using very low switch frequency (again, relatively speaking), and again poly-modding *may not* work well.

            Now, I've looked at pictures of your motherboard, and according to this picture...
            http://www.3cvillage.com/productimages/000050.jpg
            looks like you got 6-turn toroid inductors, so the CPU VRM switching frequency should be relatively high... or at least high enough that dropping the capacitance in half for poly-modding many not cause problems. Thus, using those Nichicon polymer capacitors from the Xbox 360 *should* work okay.

            Also, according to that same picture above, looks like there are a total of 8 capacitors spots on the CPU low side, but only 5 capacitors are installed. If your motherboard is like that too, then what you can do is you can replace those 6.3V 1500 uF OST capacitors and fill the 3 additional empty spots with more polymer capacitors from the Xbox 360. Eight 820 uF caps will give you a total capacitance of 6560 uF, whereas the old five 1500 uF OST caps have a total capacitance of 7500 uF. But 6560 uF is within 20% tolerance of 7500 uF, so that should work quite nicely. Let me know if you need more specifics on this or want me to clarify this more if you don't understand what I mean.
            Last edited by momaka; 07-23-2016, 09:04 PM.

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              #7
              Re: Asus A7V8X-X recap

              No help but I have the same board. Would have to look to see what version but willing to take pics. Shoot me a pm if needed.

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