Our power testing gets a new wrinkle with this review - we have moved the AMD GPU testing over to an X48 platform with DDR3 memory that uses more power than the aging NVIDIA 680i SLI motherboard that the NVIDIA GPUs were tested on. That being said, it would appear the work NVIDIA did in lower idle power consumption paid off - the GTX 260 is using much less power than even the HD 4850; at load that switches and we see the NVIDIA card using much MORE power than AMD's card.  And since the performance of those two cards is rather close, that gives AMD the nod in terms of performance per watt.