You're talking about a TEC, or thermoelectric cooler. For the purposes of cooling a pc I wouldn't recommend them. Not only does it take a lot of power (you require a TEC with 50% more power than your processor emits) but you then need a method of cooling the warm side of the TEC that will need to remove 150% of the processor output.

Phase-change refrigeration is much more efficient if low temps are your goal.