Originally Posted by larymoencurly
Every working ATX PSU adjusts its voltages. Even the original 65W IBM PC PSU adjusted its voltages.
Originally Posted by CM Phaedrus
Welp. That's a crap PSU by today's standards.
Just low powered and probably only 70% efficient, but the steel case was so thick you could park a car on it. I don't have any photos of the 65W, but here's a 130W version::
The vertical circuit board at the rear is the AC line filter and has a relay to reduce the turn-on surge (no thermistor used for that). The other vertical board, at the left, seems to do nothing but generate the Power-Good signal.
In comparison, here's a 150W Seasonic from 1986, before Seasonic became respected for high quality. The Power-Good circuit is much simpler (and incompatible with some motherboards), the transformer is smaller despite working at the same frequency as the IBM's, and originally the heatsinks at the front were just one piece of aluminum, meaning the high voltage and low voltage sides were isolated with nothing but thin sheets of rubber on the transistors and diodes (not UL approved).