Well power supply screw holes have nothing to do with keyboards. Blah Blah Blah, So what! A Ford rim will not fit on a Chevy either! Big deal.
Been fooling with these thing for years. Got 2 old HP keyboards from the late 90s, some of the first PS/2s after they changed over from the AT 5 pin keyboard connector. They work just fine on any computer I have plugged them into. And I have worked on many older computers Dell/HP and have never had a problem with newer PS/2 keyboards working on them either. Never had a problem either way.
PC eye care to show me a link about these (Proprietary) Dell and HP keyboards.