Would it work? They are 32nm die design, and they retail for about $1650 each per chip. But would it really work? Could you possibly put 2 six-core X5680 chips in a mac pro and have it work? That would be awesome if you could, I could just imagine the geekbench score on this one!! I am asking if you could put the chips in a early 2009 rev Mac Pro (I know it wouldn't work in a rev 1 or maybe rev 2 Mac Pro). But the rev 4,1 Mac Pro uses a 45nm technology with the X5570 chips. I don't know if a 32nm chip design would work in those models. That is why I ask. The X5570 is still the top of the tier on the quad core Xeons, but the X5680 is now an option for 6-core Xeon, with a steep price. Thanks EDIT: I know it won't work. The microcode is not there, and the stepping is different (B1 vs. D0). So it would never work, at least not for now. Simply incompatible, although the LGA 1366 socket is the same and the processor fits in there. The machine would fail to POST on boot.