IIRC my Gulftown crunchers at 4.2GHz were drawing 240w at the wall and make 56,000 ppd, so thats 233 PPD/w. These are barebones systems though, just a board, 3x1GB RAM underclocked and undervolted, no video, 1 HD, 1 fan and a 400w FSP PSU, not sure of the efficiency on those. I'm waiting for a good sale on a 80+ Gold PSU to see if it will make a reasonable difference.