Check my edited post
I didn't say it was best to run it that high, but what I'm saying is it can handle that temperature if it needed too.
But use common sense.
If you want to slow fan speeds down, its obvious in a low conditioned case, that temps are going to rise quite steadly over a short period.
Anything over 100 degrees C, and I'd increase the speed (what I'd do).
My GPU for example (6800GS - same as yours) is rather quiet, and I don't hear it (BFG model), but running hard in games, it gets to about 75 degrees C, which is fine. Thats running at the default fan speed though, so just keep watch
I've ordered an air extractor to put below the video card, which should cool it down by not allowing hot air to keep in the case, to have to be blown out by the fans.