I've got the pinouts for both ... it if I can use the ATX psu in this way. I'd just either cap the connections I don't need or de-solder them from the psu circuit board. Any tips or hints for ...

(ATX smps 20-pin power supply connector pinout) Next is to extend required power supply lines from the 20/24-pin smps output connector to the addon board, as shown in the circuit diagram. The add-on ...

There are a variety of integrated circuits you’ll find running the show whose data sheets will often give you an entire ATX power supply schematic ... and disk power connectors, a handy source ...

Any extra wires I cut as close to the board ... This is the power_ok to let the PSU know it’s outputting the correct voltage. That post clearly explains ATX to bench power supply conversion in details ...