Mark, you sure about that? I thought for any DC that 1 CPU core was enough for 1 GPU crunching?
I've just been looking at my HD 7950's GPU load for a few minutes & it was nearly always at 100%.
Also, I stopped CPU crunching on my 2nd rig & didn't notice any change in GPU ppd, in the short term at least.......
Yea that's odd, my Q9550 @3.6 GHz, was only showing 1.2k ppd, although I forgot to mention that was only on 3 cores.
Your Q6600's output seems surprisingly high to me!
So what was the ppd of just your 2 Xeons?