like CPU or graphics card you can set it to speed up the Fans  Asus has it for windows..

 

but is there a feature  when hard drives are getting hot..  that the fans will start increasing in speed but when its not over heating it will Run at 0 rpm or when the array are spun down they arent creating heat   so then the case fans dont need to be running probably 

 

as my asus board you can set it in windows if its not hot the case fans wont run at all 

 

There are plugins for that. IPMI plugin has fan control for supported boards, there's also the Dynamix System Autofan.

ah ok  ya this board doesnt support ipmi  i dont think.. i have a asus x570 tuf gaming-pus board  and Dynamix System Autofan  and temperature

doesnt work with the X570 boards  with current build of unraid  maybe when the next release