[Solved] Sapphire 6850 not detected, fan at 100% + other issues.

about a month ago I put together a new PC,

the specs are:

ASUS pz68-vle motherboard
sapphire radeon 6850
16 gb G.Skill ripjaws
i5-2500k
CoolerMaster 500W PSU

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.

What do you guys think the issue is?

thanks for the replies,

I'm not doing anything intense though when the reboot happens,

can it still be the PSU?

Ok, so I got a 600w Corsair builder series,

the same problem,

I turn on the PC, no video to video card, fan running at 100% constantly.

Best answer selected by epocalyptic.