Quick tests with a kill-a-watt.. stock fans speed seemed to be around 38%. Idle chassis no drives or drive bays.
2 psus, 1 psu powered, 1 contr, stock = ~34w
2 psus, 1 psu powered, 2 contr, stock = ~43w
2 psus, 2 psu powered, 1 contr, stock = ~49w
2 psus, 2 psu powered, 2 contr, stock = ~57w...