That TDP feedback control (AMD calls it PowerTune) could be a real boon to silent PCs.
Think about the 5750 which had a stock version that required a PSU power connector because it went over 75W. Powercolor made a GoGreen version with more expensive components to keep the power draw below 75W but the card costs more to the consumer.
Now with the newer cards (I suppose we'll have to wait for summer 2011 for mid range cards with PowerTune) you can use the stock circuitry put a quieter fan on it or go fanless, then turn down the PowerTune setting and bam you have a quieter card.
Imagine buying a video card without having to mod it and still being able to make it quiter just with the use of the driver control panel.http://www.anandtech.com/show/4061/amds ... -hd-6950/9
The key here is it isn't in Watts, it is in percentage. So this sort of control will be just as useful for 75W cards as it is for 200W cards. I'm not sure if it works with the 6850/6870 but it should work with all the 69xx cards and with the 7xxx and later cards in the future.