I feel that your system will be able to handle the heat of a processor at 2 volts, but I don't see why you need that much voltage. In any case I think you should get an evaporative cooler for your system. They remove far more heat, and cool to below ambient. This is really good for peltiers.
As far as the PSU that puts out 48 volts, you could make a voltage controller for it, but I think you would be better off with a 12v PSU. If you decide to go the voltage controller route, make sure the PSU puts out enough watts of energy, it's not just the volts that count here. And more importantly, realize how much current will be going through the controller, and get parts rated to handle this much and a bit more. Nothing like an unpowered peltier to insulate your processor!
edited for coherency, accuracy, and overall, content
