Well I can say we dont have the best san in the world but the good news is we are currently migrating to one that performs much better. I have never read anything that said CPU RDY was anything but a VM waiting to be scheduled on a CPU though.
I am on 5.0 U1 on AMD processors.
My guess based on what you all have said is that it has to do with disk latency. We do experience high disk latency at certain times throughout the day. I learned something new today about RDY time so thanks for that. 