I'm wondering if there is a component or a circuit that you could add to the +5v power lead coming from an AT or ATX power supply (any standard PC power supply) in order to "adjust" the power in the same way that you can from a standard arcade machine's power supply.
Is there any way to do this?
Some PC power supplies have a small POT inside for just this purpose (or really for adjustment in the factory). Open your's up and see.