How autistic are you keeping spares?
Or do you expect to move on when or before something happens?
I have my server and it's all DIY parts, I have replacements for basically everything that may not be easily gotten in 5-10 years.
>psu that's compatible with my custom cables
>mobo
>spare sticks of the same P/N RAM
>spare HDDs (more for pool health than scarcity)

I think my job is getting to me. I've seen hardware that's been operating flawlessly upwards of 14 years, but the only reason they are allowed to operate is because a few machines in the rack thay failed could actually be fixed.
Impossible to know if my machine is the one that's going to work indefinitely or need work