Visiontek 6970, screen cuts out and I get purple vertical lines

Hello,

Recently, i purchased the Visiotek Radeon 6970 as an upgrade to my Radeon 5770. Got it out of the box, plugged it in and loaded the drivers from the CD. I rebooted, and as soon as i opened up my web browser, the screen went black, flashed a few times, and then gave me purple and black lines. I rebooted, same issue. A few times, the screen flashed black and then came back with an error message of "Your display driver has crashed, but has recovered".
I immediately thought it was a driver issue, because the display worked perfectly fine in both 800x600 and in safe mode. I then went online, got the official up-to-date drivers and gave it another shot. Same issue. I had an nVidia 460 before the Radeon 5870, so i went back and made sure all of my nVidia drivers were gone. Same issue. Even did a system restore to BEFORE i loaded the drivers the first time, did a driver sweep and tried loading from scratch. Same issue.
I then tried the card in my dad's PC, same problem. I could only think of one thing left: that my POS Ultra 550x PSU wasnt up to the task of running my new card. Went out and bought a corsair 750w. hooked everything up, and now having the same problems.

I honestly cannot think of anything else, and a hard pressed to return it because of the fact that i got a very good cyber-monday sale on it. To get an equivalent card would cost me about $100 more than this one. This is not to mention the fact that if i send it back to TigerDirect, and they find nothing wrong with the card, i will be stuck with it.

Anything i could do to further trouble shoot the card further?