Xeon Phi and Tahiti are more efficient than Fermi (M2090)? I'd pretty much hope so.
That should be a given based on the fact that AMD's own marketing compares Tahiti with GF110
Nice. Cherry picking a list from the archives. You could try June 2012
(pretty much a solid wall of IBM Blue Gene), or rather wait until tomorrow when the list for November comes out. Blue Gene seems to top out at 2100 MFlops/W...
Titan used the new Tesla K20x accelerators to achieve an energy efficiency of 2,142.77 megaflops per watt (million calculations per second per watt), enough to also rank Titan No. 1 on the Green500 list of the world's most energy-efficient supercomputers.