The 80 Watt difference is also different from my calculations of 113. Here 1/3 cut, there 1/3 cut and you magically get 50% off
Its very good they at least reduced idle to great degree.
By the way,.. we are missing one more important point - not every CPU cuts power exactly when it finishes the task. So, it could be that Intel or AMD cpu is actually consuming energy *much* above the "idle" for cirtain period of time, even if they have already finished the task. You need a consumption graph to analyse that...
If I recall correctly, there was a good review of power/task at hexxus some way ago, comparing now old intel corei660 and athlon II x4/phenom II x4.