The most power-hungry CPU AMD has is the 955 Black Edition, which will shortly be only the second best, when in some weeks the 965 Black Edition will be launched. Our test-sample has a huge VCore of 1.350V, so we were quite surprised to be able to set it to 1.175V, quite an achievement:
The recently 905e has not much headroom, 1.05V is the lowest we can get.
The smaller 810 CPU did also quite well, with just 1.140V.
To be sure that the CPU runs correctly, we used Prime95. Normally you should run this programme a day or two, to be sure, but unfortunately we didn't have that much time. So we were happy with one run of small FFTs and one with In-Place FFTs.