Old/aging PSUs and reliability: is it just capacitors?

[LuckyBenski]

So I often turn down older PSUs when shopping for second hand parts. I'm generally of the received opinion that older PSUs are more likely to fail and also tend to lose capacity as they age.

Is this just the capacitors aging or is it down to everything, the silicon, thermal cycles etc?

I'm an electronic engineer so more than happy to replace parts if it's down to specific identifiable parts. I'm all for proper maintenance and making things last longer!

 

[LuckyBenski]

https://m.hardocp.com/article/2015/03/09/silverstone_olympia_1000w_power_supply_7_year_redux/1

Interesting read. And interesting that from what I can tell, the PSU still survived and is still performing ok. It mostly loses functionality at the top end near its rated limit right? Which is in keeping with the theory that PSUs should be considered to lose some of their capacity over time. I'd be interested in a teardown.