Without methodology for coming up with his ppd, the numbers are worthless...was this just doning one unit, the same unit on all machines and if so which one? Did he take a an average throughout a 24 hour period?
i can tell you with a 9800GT 512mb version superclocked....650,1652,950 (core, shader, mem)
approx ppds w/ WUs...
511pt units (slowest) = 3200ppd
353pt unit (fastest) = 5300-5400ppd
768pt unit (medium) = 4400ppd
1680 unit (largest less heat) = 4300ppd
my oc'd settings 650,1755,950 (core, shader, mem)
approx ppds w/ WUs...
511pt units (slowest) = 3500ppd
353pt unit (fastest) = 5800-5900ppd
768pt unit (medium) = 4600ppd
1680 unit (largest less heat) = 4500ppd
also note when I went from the older CUDA drivers that used 25% cpu per gpu to newer drivers that use 0% I actually saw a decrease of 200ppd on average across the board...
I use to get 6000+ on my 9800gt with overclocked settings before the new drivers...but I like the 50% cpu usage back that the gpus were taking...