alt Hacker NewsAnecdotally, RAM failures are more common than they used to be in previous decades, I assume due to increased capacities and smaller process nodes. Looser manufacturing standards may also play a part.
The component category I've never seen fail is CPU.
I've worked in and around datacenters for a few decades now and I've seen pretty much everything fail, but power supplies in particular do so at a higher rate than I expected. I've had one literally start smoking in my home office recently too. Luckily, it didn't damage any components, but it was pretty dramatic and abrupt -- just powered on my desktop and got nothing but a fog machine coming out of the rear fan until I yanked the power cord a few seconds later.