For a few weeks I was getting strange "random restarts" every few days, where I would be doing something (didn't put load on cpu or gpu) and I would get a streak of multi-coloured pixels across the screen followed by a system reboot. I re-formatted and re-installed windows and for the first day everything was working fine.
Then the next day I turn on the computer, it boots into windows (so I can see the desktop) but suddenly I get a multicoloured streak of pixels again on the screen and the system reboots.
When It rebooted, I got a succesful startup beep (so no error while booting) but no video output. Also the fan on the 6850 was running at 100% and keeps running at that until I turn off the pc.
I tried with an XFX 8800gt and I get video on POST but no video after (same 1succesful beep during POST). Same thing happens with my evga 8600GT.
If I plug in the video onboard even when I have the radeon in the PCI-E slot, I get video output but device manager does not see the 6850, and again the fans are running 100%.
I tried both PCI-E slots and get the same thing.
I sent a request in for RMA with Sapphire, but they are taking a long time to get back to me.