[nippoo]

This is a typical 1U server fan. https://youtu.be/YrU1D4bgn78

There's not a lot of space left in a 1U server, and to get the right airflow, the airspeed has to be much much higher as what you'd get in a normal ATX case.

Can you replace it with quieter small fans, while maintaining good airflow? Sure sometimes. Is it ever going to be "quiet"? Not a chance.

[detaro]

Of course 1U servers are the most extreme case. Having rackmount equipment at home is fine if you can put it out of the way and pay a bit of attention to what you buy - i.e. a 3U or 4U machine will usually have much more normal fans you can swap to quiet ones. Some people also swap fans on 1U switches.

[MasterScrat]

Pro-tip: removing the fans from switches make them much quieter!

More seriously: most switches will survive fine without fans if you don't use them too intensely (see eg https://www.reddit.com/r/Cisco/comments/3iu57s/home_lab_swit...)