I saw a Linus Tech Tips video on YouTube that suggested using the "Be quiet! Silent Base 800" PC case because as the name suggests it's a quiet case. Having used other cases in the past I was skeptical but that one IS indeed quiet. It's so quiet that I can actually hear my Sky box over it on the other end of my room even though my PC is right beside me!
I've also got 8 8TB hard drives which are fairly noisy and the case is still quiet. If you have only 1 or 2 drives then it will be even quieter.
I've also got 8 8TB hard drives which are fairly noisy and the case is still quiet. If you have only 1 or 2 drives then it will be even quieter.