I've read a lot of people complaining that their 1U servers are too loud for the office, home or whatever strange places people might want to put them.
Whenever I see the question asked, "what can be done about the noise", you'll see a myriad of silly answers like "you shouldn't have it at home or in your office at all", "1U servers are meant to be loud".
These all might be valid points but they're not the solution. A good example is a server we have at the office for testing purposes, it has 4 x40MM fans which are rated at 56dB (decibels!) and the thing sounds like a jet during take off.
We haven't tested this yet so don't quote us but we found some fans with reasonable airflow about 10 CFM vs the 20 CFM of the loud fans, but they're only 27dB.
We keep all of our 1U's in a small cabinet (it's worth the investment and does reduce the noise quite a bit on its own).
We've found suitable fans made by Sunon with the model # "KDE1204PKVX" and are planning to see if they are effective enough at keeping the server cool, but I'm confident it will drown out the noise.
So our solution is to swap out the noisy 40MM fans for ones rated with lower CFM and much lower decibels. It may not be the perfect or ideal solution, but it's the only way to co-exist with a 1U server in an office environment.