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Nvidia Geforce 840m issue

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    #1

    Nvidia Geforce 840m issue

    Hey,

    So today the GPU in my ASUS F750L decided to die. The laptop had a really bad liquid damage before but i cleaned everything up really well and it worked perfectly for a month now. I even played some hours of GTA V on this machine.

    Im pretty sure it is not due to thermal stress because the GPU was hitting 70°C at max. I guess there is still some residue of the liquid damage under the chip? I'd try to reflow the chip with plenty of flux and clean it in an ultrasonic cleaner but i want to ask on the forum before i mess with this since it is a quite powerful machine in my opinion.

    And no it is NOT a driver issue. I reinstalled Windows and after installing the latest nvidia drivers it BSOD'd when i open a game. it spits out the common error message VIDEO_TDR_FAILURE and shows up in the device manager with error code 43.

    Any suggestions before attempting to reflow it? I know that the chip itself could have gone bad and that heat temporarily fixes the issue which has nothing to do with the solder balls. I know about the baking voodoo.

    Thanks & RIP
    Tags: None
    #2
    Re: Nvidia Geforce 840m issue

    Hi,

    I had a similiar problem with a graphics card today. Actually reflowing the GPU helped. Hope this helps.

    Comment

      #3
      Re: Nvidia Geforce 840m issue

      Hi,

      Thanks for your reply!
      You did this today? Im aware that heating the GPU fixes it for some days or even just until it completely cools down again. I baked many graphics cards before (Nvidia 8000 series) and they all failed again after a while. Back then the problem was that the connection between the die and the substrate failed and heating it fixed this for an unknown period of time.

      But still thanks for your suggestion. I'll wait for some other reports and if everyone tells me to reflow it... so shall it be..

      EDIT: I googled for some time and it seems like no reports of failing 840m's exist. So i guess there is still some nasty sh*t under the chip or the vram?
      Last edited by KvnTM; 05-17-2018, 01:40 PM.

      Comment

        #4
        Re: Nvidia Geforce 840m issue

        I think a 840M shouldn't die by itself, but you never know.
        You really need to make sure it's not a software issue first so you should try another Windows installation (older maybe), and you should try to update the iGPU drivers too.

        Now if it doesn't fix it, if it's your machine and you actually need the GPU to work properly you could try first to heat it without reflowing (200°C for 2min with the hot air station) to see if it changes anything. If it does, the GPU is dead.
        If it doesn't change anything, it could be many things (still including the GPU itself) but you could indeed try reflowing the VRAM. For the GPU itself, chances are really high to kill it so that may be the last attempt only and I wouldn't try it if the laptop works normally outside of games for now (better have a laptop that you can't play games on rather than a brick). You may try to flow some flux under it but I don't know if it will help. Try ultrasonic first.
        Last edited by piernov; 05-18-2018, 04:40 AM.
        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

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          #5
          Re: Nvidia Geforce 840m issue

          Hi piernov,

          I guess they shouldnt die. Yes.
          BUT the Laptop had so much coca cola in it im wondering it is still working after i cleaned everything properly. I used it for about a month now without any issues. I put it to söeep a few days ago and yesterday when i fired it up again it gave me the BSOD.

          I‘ll heat it up as you mentioned and see if it changes something. If it does im sure its dead. Im not scared if reflowing the vram because i did the same on another laptop. It was the ram but doesnt matter. The chips are practically the same. I applied lots of flux, preheated the board and ramped the temperature up until i could jiggle the chips and waited 5 more seconds. I did this on 8 chips and it worked perfect.

          As for the GPU im a little scared of popcorning it. I have a temp. Controlled hot air station but still.. Do you know a ‚safe‘ temperature for reflowing the GPU? I heard something about 217 - 220C. But this will be my last resort. If it goes bad completely i‘ll just cut the power rail to the dedicated GPU.

          Comment

            #6
            Re: Nvidia Geforce 840m issue

            Well I recommend you not to reflow the GPU. Just heat it without reflowing. If you think something got stuck under it, get some flux to flow under it (flux melts way before the solder) for example, and clean the board with the ultrasonic cleaner if you have one. If you don't have a BGA rework station it is very easy to burn the GPU.
            OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

            Comment

              #7
              Re: Nvidia Geforce 840m issue

              Before trying reflow do try what piernov suggested, just that i would use Isopropyl alcohol instead of flux. Pour alcohol on one side of the GPU with the board slightly tilted so you see it flow out the other side. Then use your hot air station set at 250-300C to heat the board from a small distance and boil the alcohol underneath the BGA. The bubbles created by boiling will clean the underside of the BGA to some extent removing parasitic resistance and capacitance between individual connections, possibily enough for it to operate correctly.
              Originally posted by PeteS in CA
              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
              A working TV? How boring!

              Comment

                #8
                Re: Nvidia Geforce 840m issue

                Ok i will try that. But heating the gpu to 250-300°C will probably melt the solder balls and "reflow" it anyways. I guess 200°C would be enough. Ill try it without alcohol before to see if it actually is the gpu itself that failed. If it still doesnt work after the heat treatment i am very confident that either the underside of the BGA is still flooded with nasty stuff or the solder balls went bad.

                Thanks for the Help. Amazing Forum!
                Ill report the results later. It is about 1 in the morning here.

                Comment

                  #9
                  Re: Nvidia Geforce 840m issue

                  Air set to 250-300C on your hot air wand will NOT heat the GPU to that temperature, unless you keep it on for minutes. The alcohol takes a few 10s of seconds to boil, nowhere near enough time for the solder to get even close to melting point.
                  Originally posted by PeteS in CA
                  Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                  A working TV? How boring!

                  Comment

                    #10
                    Re: Nvidia Geforce 840m issue

                    I did what you guys recommended and it works again. I hope it was just junk under the GPU. But i will see that in a few days. If it fails again then the chip is dead i guess. I have some really runny flux which is like water. I used this to flood the chip and vram and then heated it up to 200C. Same with the alcohol to clean it up. We will see how it goes. As for now it is working and currently running GTA V for testing.

                    EDIT: 5 Minutes in and i got red pixels everywhere. I guess the chip went bad, hm?

                    EDITEDIT: It was just the LVDS Connector. Sorry!
                    Last edited by KvnTM; 05-19-2018, 10:24 AM.

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                      #11
                      Re: Nvidia Geforce 840m issue

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                        #12
                        Re: Nvidia Geforce 840m issue

                        Originally posted by KvnTM View Post
                        EDITEDIT: It was just the LVDS Connector. Sorry!
                        Red/magenta pixels everywhere, without the system locking up or crashing is almost always an indication of a poorly seated or damaged LVDS cable, or, in some cases, a bad screen. Bad GPU will commonly give blue or yellow pixels and usually in patterns, together with crashes in intensive programs and games.

                        Glad that you got it going.
                        Originally posted by PeteS in CA
                        Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                        A working TV? How boring!

                        Comment

                          #13
                          Re: Nvidia Geforce 840m issue

                          Still running fine. I hope the gpu isnt dead. I will see that after a few weeks.

                          Thank you. Amazing forum!

                          Comment

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