I'm not actually interested in doing it myself but "I'm just a curious little rhino". Any time i look up Peltier cooling they always seem to apply it directly to the CPU. Now, that seems to create a fair amount of internal heat. Could you not circumvent this by applying it to a radiator coil and allow the water/liquid to pass by that and have the Peltier sit on the outside of your case? As opposed to air passing by the radiator to cool it. To prevent sub freezing temps, apply some sort of PWM? If anyone knows of any examples i would be interested in seeing it.