I just got a XFX 6870 for this board and it was able to run it fine. I am using an Antec 550W PSU. Could be something specific to that card or model.
Thanks for your reply, that kinda confirms what I discovered last night.
After I took advices from you guys, I gave it one last shot and used my PSU in his system. Nothing changed.
So after som talking back and forth, we decided that he would get my 2 x 4890's and some cash, I'd get his 5870 and we'd call it a day.
As you all know when you get new hardware there's a thrill you get from benchmarking the **** out of it, so naturally, that's what I did. Ran som 3DMarks, no problem, and thought I'd wanna play some Black Ops and see how it goes. 5 minuttes in to the game I get a gray screen and the computer locks down, wtf I thought and remembered I might have altered some RAM settings in BIOS the other day, so i did a reset and tried again. 10 minuttes after I get horizontal gray lines, the screen flickers, and small black and red squares apear all over the screen and the computer crashes again.
I then pulled out the card, gave the connectors a cleaning and doublechecked all power cords etc. 10-15 minuttes in, same crap happens.
I then updated my mobo BIOS as well as the avalible BIOS update for the gfx, and rebooted, not even passing the boot screen, the card does the same with the lines and squares and then goes black. I haven't been able to make it post since and my mobo also tells me through error led's that the vga i screwed.
EDIT: I forgot to mention that I think the card suffers from a fan speed control malfunction. I noticed the fans rpm not changing during full load maybe causing the card to overheat and crash, explaining why the errors didn't occur to begin with. I think the overheating probably damaged the card and that's why it won't give any sign of life now. I had 2 x 4890's in the mashine before and I remember when things got hot, these babies reminded me that they where there to kick some *** and made damn sure that I heard about it
The 5870 has been to my, wondering surprise, very very silent.
Status now is that I RMA'd it and am waiting for a new card, hopefully one that isn's screwed
I want to thank you guys again for your help and advice.