Try the contact cleaner in every slot, reseat everything. Contact cleaner inside every socket and on every SIMM/cards + scrubbing with a Q-tip every edge pin connector.
Agree with
@MrFahrenheit the little knobs in the CPU card are probably important. Having a spare CPU card does help when diagnosing these machines.
CUDA is weird too, I think these machines are CUDA. Have to reset before you might get a chime/video.