Is there a specification on input operating voltage and frequency range for ATX power supplies? The focus of what I am finding is on output voltages.
Also, regarding just the input voltage, most appear to operate from 115 OR 230 VAC. But I want to know what tolerance they can handle around either of these voltages. (I also need the tolerance for the frequency around 60 Hz.)
Yes there is a specification.
The voltage tolerance has two ranges:
*90-135 VAC for nominal 110V range, and *180-265 VAC for nominal 230V range.
This does not depend on the mains frequency, it must work for the whole 47-63 Hz range. For EPS12V supplies the range is a bit different; it must work down to 85VAC.
Section 3.1 of the Intel spec for ATX PSUs (which I found at https://paginas.fe.up.pt/~asousa/pc-info/atxps09_atx_pc_pow_supply.pdf ) states The power supply shall be capable of supplying full rated output power over two input voltage ranges rated 100-127 VAC and 200-240 VAC RMS nominal. The correct input range for use in a given environment may be either switch-selectable or auto-ranging."
