Seasonic has a new group of PC power supplies that has amazing regulation. I have one of them in my gaming rig. In this review the 12V rail from 6.38A to 82.94A of load the voltage swing was from 12.263V to 12.266V.
https://www.tomshardware.com/reviews/seasonic-prime-ultra-platinum-1000w-psu,5397-4.html
On my particular example using the motherboard monitoring with anything from idle to the 600W I can load it up with on synthetic benchmarks I've never seen it change from 12.168V full stop. I've built at least a dozen PCs over the past 25 years and never seen anything like it.
PC power supplies are not really small and very well ventilated and not really cheap either.
Usually they run well below their maximum ratings.
Mostly the ones giving up the ghost are the ones in cheap DVD players, wall warts and some bricks. Certainly MOST of them keep working but not all of them.
It seems Restorer-John and I have both been in the repair business for over 30 years and have seen and remembered our share of failed parts.
The 'skewed' part may be that we only got defective equipment in our hands and often could already see from the type-number what would likely be the problem with certain devices and be proven right almost every time.
People come to us when something is not working, not when something works fine.
So when over a short time period a bunch of SMPS collect in the rubbish bin and almost every device these days comes with wall warts, bricks or crappy (cheap) built in non ventilated SMPS we sometimes may get carried away and call them all crap.
In my experience (repaired quite a few) the root cause is almost always the 'start-up' capacitor. This one is almost always mounted very close to a heat sink and is supposed to dry out and stop functioning
before the rest of the caps dry out and can cause massive failures and perhaps even start a fire inside. Them being plastic doesn't help. So there is a time-bomb in there on purpose.
Once the device is switched on it will keep on working till it has been switched off or disconnected from mains and simply won't start up the next time.
To get it working again usually the secondary side caps (the bigger ones) need replacement, with the correct types, don't use generic ones but with the correct ESR ! and re-solder parts that became hot and the transformer as they may have 'solder-rot' and on the primary side the start-up cap.
Sure I can see many testimonies of SMPS working fine but that doesn't mean some cheapies are crap.
Basically not
all SMPS are crap for sure but can see why Restorer-John is irritated with them bricks. It mirrors my experience.
