Intel® RAID Controllers do not support drive power save. The feature is disabled because inconsistencies were seen with HDD reaction times for power down and power up. This issue can be seen with the same HDD models that just have different drive firmware levels.
Sometimes disks took too long to power up, and the result was a drive being marked as failed. The controller firmware was changed to disable the power save feature, even though the capability in the BIOS or web console still shows.