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7800 GS AGP volt mods, 2 success 1 failure

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  • 7800 GS AGP volt mods, 2 success 1 failure

    I volt modded a 7800 GS AGP, and did the two pencil mods right, ( VDD and VDDQ ).

    only when i did my 100k ohms VR to ground, no GPU voltage change when resistance it lowered.

    I did the over current protection mod fine, i just cant change my GPU voltage.

    Any ideas?

    Site from witch i found the mod... http://sg.vr-zone.com/?i=3317
    Last edited by liquidcooled; 10-01-2006, 12:24 PM.

  • #2
    has any body done this mod here? please help!!!

    Comment


    • #3
      Do you have some pictures of the mods you did.......

      The ones on VR-Zone dont show the ground points for the 100K VR.

      Comment


      • #4
        Hi lc... lets see if we can figure out what went wrong.

        First; are you ABSOLUTELY sure you removed the correct resistors for the overvolt protection?

        Second; are you sure you have the vr solderd to the correct point?

        Third; how are you checking voltages? Are you using the point in the pic to measure vgpu voltage? What voltages are you showing now?

        Answer these questions and we will work from there, this is a pretty simple mod and it shouldn't be hard to get it working, has to be something simple.

        PS: a 100K pot is very slow to change voltages, how far have you turned it trying to raise your voltage? It may have to go quite a few turns to show any change. ALWAYS turn the pot while the card is powered up and with a dvm hooked up to see the change.

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        • #5
          Originally posted by RotorHead View Post
          Do you have some pictures of the mods you did.......

          The ones on VR-Zone dont show the ground points for the 100K VR.
          Any ground point will work. You can even ground it to a ground wire in a molex from the psu.

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          • #6
            Ok, cool, thanks bos....

            Comment


            • #7
              http://www.xtremesystems.org/forums/...t=90461&page=2

              There lost of back and fourth here on this web page above but no real answers, i even had to join there forum to try to get an answer.

              Got the pic from here, and mine to show you what i did below.

              My card is a BFG, And i heard that there have been some problems. Someone said to use a 250k VR to ground but this was not confirmed. i have scoured the web on this one and cant figuer out whats wrong.

              yes im using all the reference points from VR-Zone, Memory mods are fine (500/800!!)just gpu voltage does not change, Watercooling is ready, just need to figuer this one out.

              Vgpu=1.307_2d and 1.430_3d

              Site from witch i found the mod... http://sg.vr-zone.com/?i=3317
              Attached Files
              Last edited by liquidcooled; 10-03-2006, 04:13 PM.

              Comment


              • #8
                Ok... looks like you have the correct points modded. Are you sure you are on a good ground?

                It would help if you would answer the questions I asked above. How are you measuring voltage to the gpu? Is the voltage the same as you measured before the mod?

                Going to a 250k vr is not a good idea. I'm suprised to see them recommend a 100k.

                Main thing is... we need to know what voltages you are getting now, if they are different from stock, etc. Are you turnig the vr while the card is powered up and monitoring voltage? Does it change at all if you are doing this?

                Comment


                • #9
                  Sorry... just read your reply again and see the voltages you are getting.

                  Are you adjusting the vr while the card is powered up and monitoring voltage?

                  Comment


                  • #10
                    Yes powered on, and using a DMM to record voltage, 1.307v 2D 1.430v 3D, sorry i was editing my post to answer your questions, cause i have to doodle on the pic a little.

                    Comment


                    • #11
                      There are only a couple of possible problems.

                      1. You don't have a good ground or bad solder joint to the hot side of the vr mod.

                      2. If you are certain the solder is good and you have a good ground then chances are you are just not turning the vr far enough. A 100k vr may have to turn a lot before you see any change. For instance, if it's a 25 turn vr, you may have to turn 20 turns before you see any change in voltage. Be careful though, once it does start changing it will likely change quickly with minor turning of the vr. Thats why you want to use as low a value vr as possible for the application.

                      Comment


                      • #12
                        I tested the ground by putting my multimeter on the molex plug center ground and used a s-video shell ground point (Tested 00.00 resistance)

                        then bought 30 AWG wire fresh iron, solder, new 100k and 200k VR's. and the mod looks perfect.

                        Solder joints look great, very percise.

                        I have tried it a few times now with different wire VR's.

                        Have a 200k ohm on there now.

                        Is there a different point to put the VR?

                        Comment


                        • #13
                          Thanks for posting all this stuff guys. Interesting stuff, way over my head and skill level at this point but I feel I am headed here eventually.

                          Question: What kind of soldering kit do you guys use for this small scale of work? You guys probably have one of those magnifying glass things with a light mounted to it on the workbench too eh?

                          Comment


                          • #14
                            I can't help you with an alternate spot for the vr... they usually wouldn't have it posted on vrzone if it wasn't correct.

                            Have you tried turning the vr all the way down and still get no change? I sure wouldn't go with a 200k vr, the 100 is a much better choice. You have to figure if it's a 20 turn vr, then the 100k pot should change so much in each turn, a 200k vr has to change twice as much in each turn, making it a lot touchier when you get to the range you need.

                            Check your vr while it's off the card and watch the resistance change as you turn the pot... they don't always scale the way you think they will. Sometimes you have to turn them a lot to start getting any change, then it could change very quickly.

                            Comment


                            • #15
                              Originally posted by joeMan View Post
                              Thanks for posting all this stuff guys. Interesting stuff, way over my head and skill level at this point but I feel I am headed here eventually.

                              Question: What kind of soldering kit do you guys use for this small scale of work? You guys probably have one of those magnifying glass things with a light mounted to it on the workbench too eh?
                              Hey joe.... I use a digital Weller soldering station. You don't need that good of equipment, but I do a lot of soldering in my work. The lighted magnifying glass is mandatory.... especially at my age If you do plan on getting into it, a good iron is a great investment which you won't regret

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