To change the fan speeds on a SuperMicro X8 board (I have X8DTL-iF) there's a tool smx8fancontrol
Now there's a few deps that are needed and it's a pain to install them on UnRaid. So far this has been my script to get it to run:
# https://www.ikus-soft.com/en/blog/2017-10-01-supermicro-x8-controle-ventilateur/
# install smx8fancontrol on unraid
# install nerd-pack and enable `python3` and `pip`