[citation][nom]pocketdrummer[/nom]And I'm basing this claim on my use of the 7800GT CO, 9600GT (super quiet), and GTX570. All cards are practically silent at idle and are well below the volume level of the game under load.[/citation]You realize that power draw and noise levels aren't tied at the hip? AMD cards traditionally are more power efficient. Some of them are louder, but that has more to do with the cooling solution selected, and the desired operating temperature for a given load (how aggressively the fan(s) ramp up).
So yeah, in the past couple of generations, AMD has typically had the edge in power consumption. Since Kepler is looking to be another monster chip, I suspect that will continue. Now the performance crown, that's another question entirely.