Lower the room temp the fans wont run as fast there by will run quieter.
Make sure the miners are clean 4mos of running and i had to blow out the dust bunnies they were driving temps up.

I drool over this idea http://www.grcooling.com/ they would be silent

I wonder if anyone has tried to submerse a antminer yet

The C1 is liquid cooled its a bit quieter. But the above link man that would be sooo sweet