expreview's power consumption measurements were done during Furmark which is known to cause RV770s to draw power more than in
any other benchmark. Thus using Furmark for powr consumption testing makes no sense as it doesn't represent any real world scenario.
Xbitlabs measures the exact power draw of the card itself (during loop of 3DMark06 SM3.0) and their figures show HD4870 consumes 6 watts more than 65nm GTX260. And since 55nm GTX260 draws 10W
more than 65nm GTX260...
:fact:
Idle figures?
Reference HD4870 bios has quite conservative PowerPlay settings for the hungry GDDR5 - users can downclock their memories and cut ~40W... That's a "no-can-do" on GTX260.