Unfortunately, I've already tried checking temps. Doesn't go above 70c while playing Crysis. Hell, it only hits 80c in furmark.
http://www.youtube.com/watch?v=nkz6J-jD5P0 <-Look at the outline flickering around the foliage with the water behind it. First save is very high water with 0x AA, second save is very high water with 8x AA almost fixed issue, and third is low water with issue completely gone. Also note that setting the water to medium does not fix it, only low.
Yeah I can definitely see an outline.. Really I don't know what to suggest, I would say RMA the card, however I expect who ever you RMA to will just test the card with Furmark (or similar) and obviously its fine in Furmark so they will say there's nothing wrong with it.
It's not an issue with the card to my knowledge.
I did some more examination, and what it's trying to do si render a reflection of the things it's outlining in the water. When the AA is at 0x, it shows up as a strange flickering outline, but when it's at 2x or higher, it actually renders the reflection properly.