I am having problems with CS:Source and my new X850XT still. I played for about half an hour without any problems then all of a sudden the messed up "checker board" textures starting coming back. Once a wall or model is messed up it stays that way, it doesn't come and go. I am running at stock speeds, but RivaTool said my core was at 57 C when the game was running. Isn't that pretty hot for the core at stock speeds? The ambient temp is about 39 C or so when the card is running. Should I exchange it or do you not think the card is at fault?