Have u try it on different game?
Yes, no artifacts whatsoever in other games.
Only time I got a small artifact was when I overclocked it to way higher speeds. Even then the artifact only showed up once during the beginning of the game (modern warfare 2)
I think it's just Last Chaos. I think the artifact happened because I alt+tabbed out, then re-entered the game. It took awhile for it to get back into the game so that might be what caused it.