I am using version "LEDE Reboot 17.01.4 r3560-79f57e422d / LuCI bos+/stable-21.04 branch (git-21.099.47497-5c3e5f9)" on an SD card for a couple of S9's.

The fans constantly hunt up and down +/- 80 rpm, changing speed about every 6 or so seconds. Chip temperature is 80C and varies +/- 0.15C. Although the S9's are in a location with noise abatement, it's the sounds of the varying fan speed that's annoying. If the speed was more constant (which happens with other S9 software) the sound would be much more tolerable.

Seems to me that there should be more dead band in the control loop. We know power draw and therefore heat varies constantly as hash rates change every second. So trying to chase the temperature with varying fan speed is pretty fruitless.

Are the temperature loop tuning parameters exposed in any way so that I can adjust them?