Announcement

Collapse
No announcement yet.

I broke my 6700xt after doing a copper shim mod

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    I broke my 6700xt after doing a copper shim mod

    Hi, I broke my 6700xt after doing a copper shim mod, w/ thermal paste and pads on everything. Probably a bad idea, but IDK exactly what went wrong. I'll make a post later with some pics/ diagrams. But currently , there's no output, even in Linux. And I've started making my own schematic in LTSpice and marking up some pictures of it.

    And I've never worked on a GPU before, but I'm pretty familiar with LV power electronics.

    I see some 5700xt's look pretty similar, anyone know were to find some good threads/discussions, or info stuff similar to 6700xt and it's IC's ? How similar are the r7/r9 cards, then the rx400's, rx500's ??

    I've downloaded a lot of the IC datasheets already, but there's none for the vcore VRM controller IR35217.

    Also I'm just learning the names of some of the voltage rails on a GPU, and then AMD vs NV names and voltages aren't exactly the same. I've seen 1 video on the startup sequences.

    my 6700xt seems to have no shorts. I just finished washing it again, I literally put TIM all over the place, under the thermal pads and copper shims. Pretty soon I'll have to try it with a PSU and PCIe 1x cable, just for power, see what rails are really working.

    #2
    Re: I broke my 6700xt after doing a copper shim mod

    The history was, I did the thermal pad and shim mod, then after that it would load into a new windows install, w/ DDU disabling the intel iGPU update, but I would get a black screen, as the AMD drivers installed. Same thing on another PC.

    So I took it apart, cleaned it fairly well, and only put back new thermal pads. But the same thing was happening, even in Linux.

    I had it running for about 30min in Linux, and it started to artifact, and I shut it down almost right away. Then I tried rebooting 2-3 more times, and it had artifacts in BIOS and then it just stayed black screen, even on the BIOS loading screen.

    Physically and w/ it unpowered probing with a quality DMM, it all fine.

    When I did the shim mod, no copper looked like it touched anything, I had tons of thermal paste all over the place, IDK if that caused too much AC leakage when the core tries to go full speed, or the vram.

    I probably had the pads a bit too thick, and tightened it down a bit too much, that might have broke a solder ball loose ???


    Now I've cleaned it really well again, w/ soapy water, and 99% ISP, and drenched it in ISP at the end, and left it to dry in a furnace room, then under a fan overnight.

    I've found where most the enable and PWRGood type signals should be, but I've not checked any voltages yet with it plugged back in, that's next.
    Attached Files
    Last edited by MasterCap; 07-25-2022, 09:54 AM.

    Comment


      #3
      Re: I broke my 6700xt after doing a copper shim mod

      u broke ram chip ball. probably wih bad shim thickness

      Comment


        #4
        Re: I broke my 6700xt after doing a copper shim mod

        Ok thanks, I used shims 1/2 the size I expected, in all places, because I used pads as well. The shims I used were around 0.4-0.9mm, and the pads were 0.5, 1 and 1.5mm. I also had put TIM, pads then shims under the core, instead of the stock pad.

        IDK about the 1st time, but when I put it back together the 2nd time, with just extra pads, and the stock pad under the core, it did look a tiny bit warped. IDK if it was the BP or the PCB tho.

        Yeah so later today I'll power it up, I haven't soldered any wires on, so I won't try touching much around the vram besides a few caps, too easy to short something.

        If I can get video from it, in Linux, I'll try 1 of those vram testers.

        Some resistances I read in 4-wire mode are, 0.2496R core (reads ~0.310-0.350 on 2wire mode, 102.6R Vddram, 24.1R on the red rail in my topside pic, 1.6387R on the pink mem controller I guess, 20.2R on maybe the PEX inductor just over the right edge of the PCIe, 570R on the inductor below the Vddcore cap's

        All the rest of the rails are over 1k, and the regulator, I guess is 5v, it only reads 127R.

        Well I guess I should power it up then.
        Last edited by MasterCap; 07-25-2022, 03:30 PM.

        Comment


          #5
          Re: I broke my 6700xt after doing a copper shim mod

          I just got it plugged in, ready to power it in a mobo, and I was checking resistances, and just since I measured those ohms above, I found a dead short on Vddram. I also just dropped a little pair of scissors on the PCB, 5min ago, or maybe I also zapped it with static when I touched the ram after sitting down, although it's the summer, how bad can that be ???


          But I kid u not, Vddram was 103 2-3 hours ago, now it reads 0.1, and I never even had the standby power on the PSU turned on for days, so there's no way it was anything from the mobo or PSU.

          It's off the heatsink now, all thermal pads removed, not plugged in, and the short remains.

          So did I just break a cap, the siccors landed on the backside, right over the ram. Or did or shake loose some solder ball, just laying it on top the heastsink, or zap it with static ???


          Thank god I found that before powering it up, I might have thought the ram was turned off, until smoke started coming from somewhere.
          Last edited by MasterCap; 07-25-2022, 06:43 PM.

          Comment


            #6
            Re: I broke my 6700xt after doing a copper shim mod

            The ram voltage rail was down to 45mOhms, I found a cracked cap under 1 of the vram, using voltage injection, I was able to see where the voltage was lowest, then around 1/2W, 0.18V at 2.8A, I could very easily feel the cap burning my finger. I think it's a 0402 or 0603 smd size.

            I absolutely hit that with the scissors when they bounced off the PCB. So I'll have to use hotair to remove it, and also a mirror copy of it, to get the size. All my own caps are cheap ebay ones, I guess I can pull a cap off a modem or something, so I hope it's a common size.

            Comment


              #7
              Re: I broke my 6700xt after doing a copper shim mod

              Ok I got the bad cap off there without burning the PCB, using a cheap 858D. And that was the only short, unless the core is toast, because it sure gets hot.

              So with it connected by a 1x PCIe cable (waiting on a proper 1), and it's 12V, I get the following voltages, until a bunch cut out. And it seems all of them can be tested from the backside, so that's great for now, I have it on the cooler.

              See the pic below

              Pink=0.91V , I guess that's memory controller
              Purple=0.92 Vddcore which sounds about right for some idle state, but damn it's hot under the core
              Red=0.815V , 1 of the main phases
              Brown=1.36 Vddram

              Light blue just under PCIe=0.75V
              Neon Green under PCIe=1.81V

              Dark Red=5.04V ,3-terminal reg
              Orange by above reg=5.04V, thats Vcc for the DrMOS, but not from the reg. above
              Green near 8pin =5.06V, for the fans,etc

              12V looked ok, I forget to check mobo 3v3 in (it mainly goes to the MCU, not the DrMOS orange)

              This in a PC w/ no hardrive, and I get no video at all, and after 20-30s, the GPU turns off all voltages, except the all three 5V rails, and the 1.8V rail.

              The caps under the CPU really get hot by then, but they always did run hot, but I can't rule out something's overheating in/around the core.

              After a quick look w/ an oscilloscope, all looked fine, except I never saw any activity from the BIOS chip, not p5-6 anyways, and Vcc was there.

              I'd really like to find any overtemp sensing pins from the core, IDK if that all gets fed to the MCU. Or maybe see what current is being detected by the various DrMOS or controller's, maybe something is using way too much current.

              I'll have to start looking for power good signals, and enable lines.

              What does this sound like ?
              Attached Files
              Last edited by MasterCap; 07-28-2022, 01:43 AM.

              Comment


                #8
                Re: I broke my 6700xt after doing a copper shim mod

                Ok with some wires soldered on, the EEPROM is definitely being talked to, right at the beginning anyways. IDK how all that works, whether if it's the microcontroller that talks to it, or if the mobo talks to the GPU BIOS chip or only to the GPU micro-controller, etc. And there's no monitor connected ATM, IDK what exactly it talks to on the GPU.


                The back of the core is only hitting 55-60C before is shuts off, but it rises fast. But again the back often felt hot in the past, which is part of the reason I did a copper mod, and placed intel heatsinks on the backplate.

                Looking at the startup voltage timing's it basically matches the order in the video I saw on it, IDK the exact names or which is which, but they all look pretty normal to me as far as DC-DC converters go.

                And they all seem to shutdown at almost the same time, with the PCIe 0.75V being the yellow trace below, it's supposed to be the 1st to start after 1.8V, and it looks like it's the 1st to turn back off.


                on the scope

                yellow is PCIe 0.75V
                red is the main Vcore
                blue is Vram
                green is the pink phases, 0.91V probably the other core voltage

                and in the last 2 pic's red must be the the memory controller (and red on my PCB pic's)


                So time to check some stuff on the topside, but without a boardview, I will be lucky to find the logic circuits for the various enable signals.

                The game continues
                Attached Files

                Comment


                  #9
                  Re: I broke my 6700xt after doing a copper shim mod

                  u know why is cooper shim used? to eliminate pads!

                  Comment


                    #10
                    Re: I broke my 6700xt after doing a copper shim mod

                    Yeah and making a sandwich with them is pointless too, but in some places I put pads under them, as an electrical insulator.

                    But great news, the GPU is still alive, after some set backs, I saw video from it tonight.

                    2-3 days ago when I was testing it, without it on the heatsink (but with a little 1 and fan), the voltages were not cutting out after 20-30s. but I still had no video.

                    I had cleaned the PCB much better again by then, and used lots of IPA before drying it. So IDK what really changed, besides not being upside down on the heatsink.

                    I had been attaching a bunch of test leads to unused 0402 pads and resistors, and the wires were to big and stiff, no joke. I broke a few pads, and lifted a couple of resistors by accident, repairing the pads. I lost 1 with the solder, never even realized that happens so easy with 0402. So I had to calculate it from the datasheet for the 1V8 buck regulator.

                    Now I fixed all that, I have all my voltages back. And I tried a video output, and it actually worked, I got into BIOS. Thats the 1st image I've got in weeks.


                    Now I'm still expecting problems when I install the drivers. So I'm setting up my Linux machine first.

                    I still want to get a bunch of wires on it, to see what happens when it tries to install drivers, or maybe go full speed. But that's pretty dangerous. 0402 traces are so small, it's a nightmare with only 2 hands. I can at least look at each phase's, I/O voltage on the scope. There's plenty of safe places for small wire too, I just need to wash it properly, then glue it down 1st I guess.


                    What is the list of programs I need, to test this 6700xt in Linux ? I've downloaded a few random vram testers, but IDK what they were called, or were they are ATM.
                    Last edited by MasterCap; 08-06-2022, 01:28 AM.

                    Comment


                      #11
                      Re: I broke my 6700xt after doing a copper shim mod

                      Ok the other day in Linux, using just the 6700xt, I was able to run dmgg.py, and it reported no errors for 255MB test.

                      Then I was able for the 1st time in ages to install the drivers in Linux, then in windows. And I was playing an older 3D game with the FPS locked to 60fps, then I unlocked it, and my temps got really really high, like 115C hot-spot after a minute.

                      I didn't really believe it because I had the fans set to max. Then later I tried running BF1 and it was 70C in the menu, and then as soon as the server loaded, the PC shuts down.

                      As it turns out the cooler was only over half the die/thermal paste, I think related to my thermal pads, it does fit ok, but not that time.

                      So now tho, all big and small phases are running and look good, I can see each inductor firing on my scope, but I've had no video at all since that thermal shutdown.

                      So I have to boot from the iGPU, but then both windows and Linux can detect the other GPU as a 6700xt, and linux gives lots of info. Windows says error code 43.

                      When I just ran dmgg.py , the terminal curors jumps to a new line, and acts like it does something for maybe 20-30s, but then gives no info, it just goes to a new prompt line $

                      Also, when the GPU is connected, it will override the iGPU, so it never turns on. Also it seems to POST, I mean it makes 1 beep just like a normal POST, but there's never any video at all from any O/P.


                      So there's plenty of life still in it, but have I really dislodged a vram or a core solder ball this time ? Or fried some little part ???



                      I should never have taken this thing apart.

                      Comment


                        #12
                        Re: I broke my 6700xt after doing a copper shim mod

                        Here's what GPUz see's in windows, running off the iGPU tho, and some info Linux gives

                        For now I don't have solder balls, or a hotair gun I trust, or any experience with BGA soldering.

                        I'd need some practice before I'd try removing vram 1 at a time and see if that helps. I'm praying the memory controller is still alive. I'd need better gear before I'd trying re-balling the core.

                        I want to know how they check these at the factory, what I2C or JTAG tests do they run. I have no where near the programming skills for any of that tho.

                        And where do all those test points on the side of the core go ?
                        Attached Files

                        Comment

                        Working...
                        X