i know in this post is talking about custome firmware. But you try to reduce noise and sameone say samething about coordination about fans and sinchronize them i think its a litel bit more hard to achive it.
What i want to ask is if sameone try to put 150mm or 200mm fan to reduce the rpm and in consecuent the noise?
The noise comes from the fan, so if your place is not too hot and you can decrease the hashrate, you can lower the fan speed.
For instance, set to the lowest voltage (or 2,3) and decrease the frequency around 400, you can set fan speed to silent if the cpu temperature not so high.