Originally Posted by theonedub
With max HCC GPU WUs (I believe about 5 WUs), my 580 can do ~30kPPD @ 875core. Not as great as AMD, but I believe its better than Kepler and it far outpaces what my i7 3770K does running 24/7 on its own @ 4.2ghz (~5kPPD). Even considering that the Fermi card will use more power, it is still a very efficient way to crunch considering the watt:PPD.
My HD 6670 DDR3 does one WU in about 12 minutes (one WU at a time), a GTS 450 does about the same according to Brandonwh64 (so a higher middle class nVidia is doing as well as a lower middle class AMD of ~50 watts peak).