  Yes, it can. The BMC and BIOS work together to control fan speeds. The BMC is programmed to run fan speeds within a certain threshold based on system configuration. A minimal configuration will have a low fan speed minimum, and will increase up and down with system temperature. A maximum configuration will have a higher minimum fan speed. I don't have access to the exact settings the BMC is programmed for, but different CPUs can change the minimum fan speed settings. You might want to try reflashing the BIOS and BMC/iDRAC, and also clear NVRAM to make sure there is nothing corrupted in memory. If you still encounter the same fan speeds then that is what the BMC/iDRAC is programmed for. Thanks
Greetings Folks.. I have two R610's, one of which sounds like an airplane and the other is as quiet as a normal desktop. The quiet system runs (idle) at 24C, with fan speeds between 3000 and 4560 rpm.   The loud system runs (idle) at 18C with most of the fans around 7080rpm.   Both systems are using the latest versions of firmware and bios. The quiet one has dual X5570 @ 2.93Ghz and the other has dual X5677 @ 3.47Ghz My question is, would this difference in CPU make such a big difference when it comes to fan speed?   
R610 Fan Speeds