Well, I've had this same problem when I had 2 monitors attached, around 9.12 driver time. This time I have only 1 monitor attached, but the following happens: When I boot up, the card is at level 1 idle clocks (157 Mhz core) which is good. Then, I watch a video, the card goes up to level 2 (400/900) clocks. When I close the video, the card stays at those clocks. I'm currently at 10.2 drivers on Win 7 x64, waiting for the 10.3 suite to see if that fixes this problem. Anyone have an idea why the card won't clock back down to idle clocks?