Still do the memtest, anything can be DOA. That said, it's sounds like a graphics card issue. You may wish to interrogate your friend (j/k). What type of artifacts are you seeing? Is it crashing the game, the entire computer, or just making it unplayable? It is instant BSOD on it's own, or after period of time, or after you do something specific, like choosing and option or try to quit? I've beaten that game, so at what point are you having problems? Even though Hitman Absolution is a very demanding games, and built with AMD in mind, there is no reason you're 580 shouldn't play it at some level. Do you still have old drivers installed from a previous card? Have you tried lowest settings, underclocking, and other games? Sorry to rattle off a wall.
I removed the card, cleaned the contacts, and reseated it. The cinematic which I had trouble with (the one following the Rosewood Part 1 section) has played through with no issue.
Still noticed one small bug, but it seems not to be a big issue.
The BSOD's would be, graphics would get funky, then a bsod. Sometimes Windows would be able to recover the driver, when it didn't it went BSOD.
I'm currently running off that same friend's HX1000, going to try running the game off the CX600 and see if I get BSOD's. (If I do I'll go get a HX650). If I don't .... safe to assume it's safe for the card to run it on a slightly underpowered PSU?