Recently I got an X1900 XT so I could play oblivion better. I was getting FPS around 30 outdoors, which was great. More than double what I would get sometimes with my old 6800GS.
Now, all of a sudden, my frame rates are in the single digits outside, for no apparent reason. My card still scores almost 9000 on 3DMark05, and using F.E.A.R's built in test, it puts out 70 FPS. So it's definitely not the card. And for anyone who has played oblivion, I have no sound in the opening credits.