Miner Configuration Tab. "Customize the fan speed percentage."
Not on a S9.
I am looking at it on an S9. Miner Configuration Tab, Under the General Settings sub tab, at the bottom. It's on all of my S9's, regardless of batch & firmware version.
You must have all s9v1. There are no other tabs under gereral settings. All my firmware is of April of this year though. Let me know if it has changed in newer fw.