It IS a very common problem on this forum. There is a thread stickied with people experiencing the same issues as you. http://www.nvnews.net/vbulletin/showthread.php?t=114925
My first BFG 280 GTX OC had the same issue, I exchanged it and my 2nd card which was an EVGA was fine. Your card is bad I would RMA it or exchange it if you can. Although Furmark heats it up quicker than most other games and apps. Other games and stuff will crash, and since you are getting artifacts I would do definitely RMA or exchange it. Under no circumstances regardless of the benchmark/game being run should a card overheat to the threshold temperature and throttle.