The Tech Report heard NVIDIA is introducing clock throttling with its GeForce 9500 GT graphics card to save power when your system is idle:
The Chinese site says it discovered clock throttling behavior while testing the GeForce 9500 GT. Using ForceWare 174 drivers, the card's clock speed reportedly dropped from around 600MHz to 200MHz, taking GPU temperature down from 55°C to 50°C in the process (and, we'd wager, lowering the fan speed, although Expreview doesn't mention that).
Judging by earlier rumors about the card, this GeForce 9500 GT will be based on a new G96 graphics processor, and it will have a default clock speed of 550MHz, 512MB of 500MHz DDR2 memory, and a 128-bit memory bus. The card is expected to be a replacement for the GeForce 8500 GT, so it may launch at less than $100.