Hi people, I'm just going to pitch in on this thread because I am having the same problems. Mind you though, it is going to be quite long, but also have very detailed information because I have spent almost a week trouble shooting the nvlddmkm.sys error.
First of all, here are my specs:
Intel Quadcore Q9450 CPU (not overclocked)
XFX nForce 780i motherboard (latest drivers and bios installed)
4 GB Kingstom ram PC8xxx (not overclocked)
Corsair TX 650 watt PSU
Geforce 9800GX2 graphics card (not overclocked)
Windows 7 64bit RC 7100 (fully updated)
-------------The problem--------------
It all happened on tuesday, december the 15th. And it happened like a lightning from a blue sky. Monday evening, my computer was working perfectly, as it has been for the past 1½ years with the current hardware. I was running XP prior to getting Windows 7. I installed Win7 in around June, and have been running with it ever since, never had any problems with it at all, it's been a real treat. I even played a few games late monday night before shutting down the PC and going to bed.
Tuesday morning I power up the computer, as always. After a couple of hours uptime, of reading forums and mails and other casual stuff, I start up Steam to play some L4D2, and then during the 2D commercial, my monitor flashes, mouse cursor freezes, and then the monitor goes into standby mode. Some 20 seconds later, windows crashes to Blue Screen Of Death with the nvlddmkm.sys error (for the first time EVER, I have never had this error in the past 1½ years I've had this PC). I reboot the PC, and before windows even loads, the screen hangs for 60 seconds, and then BSOD with nvlddmkm.sys error once again. At this point I am using the 191.07 driver version for my 9800GX2.
I try an array of different things, such as uninstalling and reinstalling different driver versions (including the latest one; 195.62), via Safe Mode mostly, although every now and then, Windows manages to load without crashing. However as soon as I start up a game - any game - it crashes to standby and then BSOD. On a FEW occasions, I manage to play some games for several minutes with absolutely no issues at all. Perfect frame rates, no errors, hangs or crashes. L4D2 and Dragon Age being two such games, although at some point, either during those games or other games, BSOD with nvlddmkm.sys error occurs, followed by windows being unable to load again.
Finally I give up and reinstall Windows from scratch. After a clean reinstall, the problem persists. First game I try causes BSOD nvlddmkm.sys error, and windows is unable to boot afterwards. I had NOTHING installed other than the most essential drivers and windows updates. Reinstalling did absolutely nothing.
-------------Extensive Hardware Troubleshooting--------------
I replace my 9800GX2 with an old 7500LE graphics card I have lying around. This solves everything. No more crashes, games run (although at horrible frame rate due to it being a poor gfx card).
I then try out my old 7800GT graphics card. Once again, no more crashes and BSOD's. However, on a FEW occasions, games would crash outright, but windows remains running and there are no actual error reports as to why they crashed.
As soon as I pop my 9800GX2 back in, nvlddmkm.sys haunts me time and time again.
-------------More Hardware Troubleshooting-------------
I visit a mate of mine to borrow his 8800GT graphics card. I also bring along my own 9800GX2 card to try out in his PC. However he only has a 600 watt PSU, and is running Windows Vista 32 bit. His normal graphics card is a GTX275, which runs flawlessly on his system.
I install my 9800GX2 in his machine, and after driver installation, his windows is unable to start, hanging for 60 seconds and the BSOD with nvlddmkm.sys error. I install his GTX275 again, and everything works like a charm.
I then drive back home, and install the borrowed 8800GT card in my own machine. After driver installation, windows loads. Looks good. I start Left 4 Dead 2 to test it out, and before the game even finishes loading, the screen is littered with blue lines, the game freezes, the monitor shuts down, and 30 seconds later the whole PC goes into sleep mode. I reboot, and windows is now once again unable to load, producing BSOD 60 seconds later with the infamous nvlddmkm.sys error. Furthermore, the blue lines remain even during boot, and in BIOS. They never go away, but they are only present with the 8800 card, not the 9800gx2.
I tear out his 8800GT and install my old 7800GT again, and windows instantly starts and no more crashes.
------------Speculations-------------
I do not think this is a driver issue. It is a hardware issue (in my case, at least). I've tried 3 different driver versions - 190.62, 191.07 and 195.62 - none of them solved anything. Furthermore a complete reinstall of windows did not help.
Furthermore, the error is based on which graphics card is installed. As detailed above, I've tested 4 different graphics cards (all nVidia brand), and only 2 of them caused the issues, while the other 2 seemingly run fine. And yes, I am using the exact same drivers for all 4 cards, so the 7500 and 7800 are not working because they are running on different driver versions than the 8800 and 9800. They all use the same bundle (191.07 or 195.62).
And lastly, it happened from one day to the other. Out of the blue. I did NOTHING other than click the PC power button. Nothing had been installed, nothing had been changed or removed, nor software nor hardware. The whole system had been completely untouched. It just happened for absolutely no (apparent) reason.
I cannot imagine it being a driver issue.
So hardware then? That's the most likely explanation I can think of. The big question is what?
Is it the 9800GX2 that is broken? It doesn't work on neither mine nor my mates computer. It was my first suspect of course, but now I am not so sure. As mentioned, the 8800GT also doesn't work on my machine. Unfortunately I didn't get to test on my mates machine first, so there is the possibility that simply both cards are broken.
However, my second suspect is the PSU. I have a 650 watt power supply. It is 1½ years old now. From what I've gathered, the nvlddmkm.sys error can be cause by the graphics card not recieving sufficient power, and the 9800GX2 is very power-demanding. But it seems odd to me that a 650 watt PSU cannot even supply enough power to run an 8800GT card. Especially considering that my mate is running a GTX275 on only a 600 watt PSU with no problems. Surely a 650 watt should be more than enough for an 8800GT at least? And just to recap: My 9800GX2 has been running perfectly fine on my 650 watt PSU for the past 1½ years.
Unless of course that my PSU has broken down somewhat, and is no longer able to output the full 650 watts, but still enough to keep the rest of the PC running with a 7800GT card or less. In that regard, I tried pulling the power from all other hardware in the PC except the windows harddisk and the 9800GX2 card. And it still didn't work.
The final suspect is the PCI-E port on the motherboard. But that is just pure speculation. I don't know what kind of symptoms it would cause to have a faulty pci port. Also, I suppose, that IF the pci port was faulty, then surely there would be errors with the 7500 and 7800 cards installed as well. So it seems unlikely to be the cause, but I don't know.
---------Final words--------
So, I'm sitting here with 4 different graphics cards, 2 of which run on my system, the other 2 causing BSOD and nvlddmkm.sys errors constantly. Broken PSU, or two broken gfx cards? I don't know. And I am running out of ideas on what to do or try.
---------Addition-----------
I've just tried putting the borrowed 8800 in my movie computer, which only has a 400 watt PSU but runs no other hardware apart from the cpu, motherboard, 2 harddrives and the graphics card. And it produced graphic glitches as soon as I hit the power button, with strange lines running down the screen during startup and bios. It seems that the 8800 indeed is broken, which means the likelyhood that the 9800 is as well.
I hope when i reinstalled the windows its gona be repaired or something, but 1. i cant instal win 7 after first reboot i got black screen and nothing happens
h my rig is E4300 cpu oc 3.0ghz
