Computer power supply uses (NOT home repair topic)

Yes. Done it. There is also info on the web about modifying switching power supplies SPS. We modified such an SPS so that local radio amateur could operate his

12 volt ham rig on AC supply. The one we chose gave some 20 amps at 12 volts IIRC. (That's 240 watts). It is usually found that you have to put a small load on the +5 volt DC put for the y thing to operate at all. So we loaded it with a wire wound resistor mounted on the case that consumed about 2.5 amps, that's 12.5 watts. Something of a year later he says it's working fine. Be careful inside there can be 350 volts at something up to 20 or more kilohertz.