The setup: MacPro 2.8GHz (Early 2008 model with 8 cores, 10 GB RAM, nVidia GeForce 8800GT, four internal hard drives of a total of 5.25 TB). The symptoms: On Friday night I was booted into Windows Vista (64-bit) via Bootcamp as I had to do a bit of gaming not possible under OS X. Specifically I played All Points Bulletin (brand new MMO only for Windows). I found it to be an interesting idea to open another game at the same time (Warhammer Online). So I had both games running at once. After a couple of hours I received an error message ("Display driver has stopped responding and successfully recovered"). I had seen this message on a few occasions under Windows some months ago too. This time however the error message went away only to give me a slightly garbled image on screen. Psychedelic colours, quite funny looking in fact. I restarted Windows, and all looked normal again. Then I opened browsers, word documents and so on, all normal. But as soon as I opened a game, the display was full of distortion and funny looking colours, dots and stripes, patterns vertically and horizontally. I also received the dreaded blue screen (which I had never had in Windows on my Mac since I installed it two years ago). I booted into OS X. All looked normal. Then I opened a game. Same symptoms as in Windows. I restarted. Opened only a simple YouTube video. Even then the display was making everything on screen impossible to see (and read). I did all the normal procedures (resetting PRAM, checking on logs for hints at what could be wrong and so on). I also ran the Apple hardware test, the extended version, which lasted two hours. It found nothing wrong. I checked all connections and cables, I double checked the interiors of the Mac, no dust, all looked normal. I restarted the Mac into OS X once again, and this time I could only see the Apple logo during booting. After that it was mostly a black screen with some strange colour patterns. Sorry for the long post, I'm writing this from another computer away from home as the Mac is all I have there at the moment, and I do not have access to any of its contents from here now (no logs to show you, no photos or videos). To me this looks definitely like the 8800GT has died completely, and I will bring it into an Apple retailer tomorrow for some testing, but I thought I'd just mention this here in case you guys should have any ideas. I would like to point out that I run iStat on my Mac and that I regularly check on the components temperatures and fan speeds. Everything always look normal there (low temps in general, and fan speeds are mostly at their idle default settings, spinning up a little bit when doing graphically intensive tasks for example when video editing or playing a game). I did notice on Friday night that the power supply fan under OS X remained at its low idle setting all the time even when I tried to speed it up by using SMC Fan Control. The program managed to speed up all the other fans, but not the PSU fan. I do not know if that is any indication of something else going on. Sadly SMC Fan Control cannot control the GPU card's fan under OS X, but under Windows I do regularly control the GPU fan and temperature, and the card there has always been running between 60 and 84 degrees C. Any ideas and tips would be welcome... is this a GPU having died, or symptoms of something worse (the PSU fan speed that does not seem to want to change do worry me slightly).