I've got 3 C6100 chassis I need to fill with 6 core CPUs, anyone have any quick ideas/thoughts on which of the 6-core 1366 Westmere-EP chips consume the least power while still offering the best bang for buck? I'm guessing the answer is going to be either L5639 or L5640 but am wondering if the X5650 is going to be just as power efficient in the long run to make it just worth getting instead.