Technology

My guess

without trying to dig up statistics

is that the single component most-likely to fail in an old PC is gonna be rotational hard drives. Virtually all of my rotational drives have eventually died, aside from a few that were just so small and taking up space where I could mount other things that I no longer bothered using them.

I've seen fans die (not necessarily completely wedge up, but have the bearings go and become increasingly-obnoxious in sound).

And those are basically the only mechanical components in a computer.

Behind that, there's input devices with keyswitches wearing out, but unless you're using a laptop, replacing the input device is just unplugging the old one and plugging in a new one.

I'm not gonna say that motherboards don't fail, but I can't immediately think of something that would die. Decades back, I remember that there was a spate of bad capacitors that made their way to a bunch of motherboards and would eventually fail, but I haven't seen anything like that recently.

searches

Looks like it was 1999--2007:

https://en.wikipedia.org/wiki/Capacitor_plague

The capacitor plague was a problem related to a higher-than-expected failure rate of non-solid aluminium electrolytic capacitors between 1999 and 2007, especially those from some Taiwanese manufacturers,[1][2] due to faulty electrolyte composition that caused corrosion accompanied by gas generation; this often resulted in rupturing of the case of the capacitor from the build-up of pressure.

High failure rates occurred in many well-known brands of electronics, and were particularly evident in motherboards, video cards, and power supplies of personal computers.

A 2003 article in The Independent claimed that the cause of the faulty capacitors was due to a mis-copied formula. In 2001, a scientist working in the Rubycon Corporation in Japan stole a mis-copied formula for capacitors' electrolytes. He then took the faulty formula to the Luminous Town Electric company in China, where he had previously been employed. In the same year, the scientist's staff left China, stealing again the mis-copied formula and moving to Taiwan, where they created their own company, producing capacitors and propagating even more of this faulty formula of capacitor electrolytes.[3]

Those would probably be from the DDR/DDR2 era, though.

I do think that it's probably possible that some motherboard components might age out. Like, people may want to use newer versions of radio stuff, like WiFi or Bluetooth. You can maybe do that via USB, but the on-motherboard stuff might become more of a liability than the CPU or something.

I don't think that I've ever personally had other computer components just up and fail other than the 13th and 14th gen Intel CPUs that internally destroyed themselves. It's always been non-solid-state stuff, things with moving parts, that fail for me. I mean, I've damaged solid-state components myself via things that I've done, but it's always damage that I incurred.

thinks

Oh, CMOS batteries eventually fail, but they're usually

not always

mounted on motherboards with holders that permit replacement. I've had to replace those.

I did have a headphones amplifier that was attached to my computer where some solder joints got a bad connection and I had to open it and resolder it, but I don't know if I'd call that a "computer component" just because it was plugged into a computer.

thinks more

I did have the power supply used for a fluorescent backlight in a laptop display start to fail once. But, honestly, my experience has been that unless you actively go in and damage something, most solid state parts will just keep on trucking.