Insufficient PSU?

[CardboardSword]

I recently purchased a 6870, I found it gave me artifacts and some other weird graphical glitches on occasion. I can give details of these if necessary, but I'm not sure they matter. The card would artifact on occasion, so I thought it was bad. Now I've got a new one and I'm finding the exact same problem. I have a 550w Antec Basiq. I know this isn't exactly a top of the line PSU, but shouldn't it have more than enough juice to run a 6870? I was under the impression that the 68XX series were quite energy efficient, and with a 500w recommended requirement and a half decent Antec PSU, shouldn't I be fine here? I have no idea what else it could be if not. Please help guys I'm kinda frustrated here.

 

[Candlepally]

lower your overclock on the CPU

 

[CardboardSword]

lower your overclock on the CPU

I considered that, but then again, I'm only up .025V from the bare minimum, which can't be making that much of a difference. Maybe I'll try it anyway, see if it helps.