under the config cgminer tab change Vcore from default of 0 to -1 or -2. That will lower core voltage and the Avalon's auto-tuning software which constantly adjusts speed (and works vs Bitmains which is... and only runs at startup) will in turn reduce power used and fans will follow that.
is there a way to undervolt just specific miners or is this available for only for the whole batch (same controller)?