OK its worth looking it to this, I would try it out on one of those rigs
on the 2600K I would allocate 0.1.2.4.5.6 to SMP and 3.7 to GPU
This means that the SMP is not fighting for cpu cycles as it has its own cores and HT cores running 6 cores maxed without interference from the GPU's makes it faster and more ppd (more heat as well so keep your eye on it.
The same is true for the GPU's as core 17 on Nvidia GPU need more CPU time than the previous cores have done (for a few years now Nvidia cards have been light on CPU usage - unit core 17 that is
With my sig (and current only rig, I max out at over 85k ppd
for your 2 rigs I would expect itro
2600K 15K
680 37K
680 37K
3930 20k
690 60k
690 60k
total 169k ppd
I have no idea on the 2p :) but I guess its in excess of 130k
so I would be hoping for itro 300k ppd a bit above your current average
there is of course no promises here :)