The noise should be from the fans, those are the only moving parts of the miner. We don't have any recommendations for any fans that can produce the same amount of air movement and are less quiet. Here are the specs of our fans:
Air volume: 80.16 CFM
If you want to buy different fans, you can use this as a guide. However, be mindful of cooling if the air movement is lower.
Ok don't recommend but share with me if there are fans in market which are 5700 RPM and have Noise level of 20 DB or so?