Unfortunately PCs have mechanical devices that give out after a few years. I am referring of course to fans. I use a Raspberry Pi 4 running Ubuntu and Samba as my NAS. It is cheap and reliable.
Initially I naively tried to run the two drives right off the USB3 ports in the Pi, and that basically crashed within a day - but that is of course because I was exceeding the power draw. An external hub and supply helped, but didn't fully fix the issue.
I’m not buying anything else and I’m also swapping out any non-noctua fan in my parts when possible (e.g. bought a scythe cooler due to ‘interesting’ dimensional constraints and swapped its fan with a noctua one.)
They almost never run 100%, though, and I have a recurring task set up to clean dust outta my filters, computers and servers.
Also a fan is like $10?
Things which are more vital than that are the disks, power supply, rams.