About the same as any other 1U box. Noise is never a design consideration. I think the loudest equipment we have (aside from the AC) is a 14-blade unit. Sounds like a jet turbine when you power it on.

You have to remember, all rack mount equipment is designed to be used in a dedicated machine room, in racks with AC equipment. They are not intended to be used in a normal home or office environment. They're built to stay cool, not be quiet.