I have a PS/2 Model 80 with one giant MFM drive in it and internal 3.5" and 5.25" drives. When turned on it does nothing except the hard drive spins up and the speaker clicks as if power was applied and made it there, but no beeps and no disk drive activity. Nothing on the Sony Trinitron monitor that I attached.

Have you checked your power supply voltages with the motherboard attached (as a load)?