kagura1050 wrote on 2024-11-22, 10:59:

I think (this is just speculation) that the PS/2 combo port may be causing the problem, because it may add voltage or clock to the "NC" pins (which could affect the keyboard's internal controller).
If the PS/2 port on the other machine is not a combo port, you may want to try connecting the keyboard via a splitter.

Alredy on its way an USB active adapter that actually translates PS/2 signal into USB keyboard signal.

kagura1050 wrote on 2024-11-22, 10:59:

Off topic: I didn't think I'd meet an IIDX player here...

Watch out, we are everywhere 😏

Quick Update: The adapter worked pretty fine.
It didn't work on cold boot right away, but after enabling "Legacy USB support" in BIOS and uninstalling/reinstalling all the keyboards in device manager, it works without issues even at cold boot.