Ali Man
CPU has got nothing to do with it since x99 CPU's don't have a built-in GPU, so using a d-GPU that's folding would definitely stutter at max load.
My PPD is fine, it's impossible to get all the same WU's that really give you a high PPD, that's why I used the term 'average'.
CPU has nearly just as much to do with it as your GPU. if you try and run 5 instances for FahCore21.exe on a quad core CPU your PC will be complete unresponsive. even on a 6 core CPU with proper affinity management 5 instances of FahCore21.exe will leave only 1 core for windows and all other apps. not to mention if you are running a 28 lane CPU your 5 GPU's will only be running in x8, x8, x4, x4, x4. meaning your PPD on 3 of your GPU's will be restricted due to poor bandwidth to your CPU.
if you didn't know F@H is not a GPU standalone application. it requires 1 physical CPU core per instance and good bandwidth for the data going to and from the CPU/GPU. and again for your PPD i was getting ~2.2 Million with my 4 1070's for over the 2 weeks i had them running, and that was with them not fully boosted due to poor thermals, 95C at times.