Two new Peltier-cooled systems are made available to the public for the first time today! Why might thermoelectric cooling be the trend setting method for stable overclocking? We answer this question in our news article below.

In most of the chatter you find in the overclocking community, you find yourself inundated with Liquid Nitrogen enthusiasts looking to freeze CPUs colder than Pluto on a winter morning, although their record-setting speed attempt lasts about as long as a deep sigh. While we applaud those very few who have broken the 8.0 GHz barrier in temperatures where electrons can hardly wiggle, we also have to raise an eyebrown and wonder: Why?

The pragmatists in the group have retreated from the ever-frigid quests, and had previously found a very happy medium in a very familiar fluid: water.

Not satisfied with spawning 10 vortices and nearly vibrating computers into the next room as their fans blast away, the herd has gathered around a watering hole of a different form - the radiator. You see, water has some very useful properties. Bypassing ahesion and cohesion, and the very fortunate fact that it is most dense at 4 °C (and not its freezing point), we focus on its specific heat capacity.

Specific heat capacity (often shortened to specific heat) is the amount of heat or thermal energy required to increase the temperature of a certain quantity of a substance by one unit of measure. For example, at a temperature of 15 °C, the heat required to raise the temperature of a water sample by 1 °C is 4.186 joules per gram. This is the second highest specific heat capacity of any known substance, after ammonia. Water is, therefore, an excellent temperature buffering material, capable of stabilizing temperatures of material with which it comes into thermal contact.

In the world of overclocking, we use water the way humans use trash trucks: to haul away that which is no longer needed. The cooler radiator water circulates through the overheated CPU region, the cool temperature of the liquid is heated up, then circulated away from the CPU, functionally taking the heat with it. It is cooled in the radiator, and upon exiting, returns to the CPU chamber again. Simple, efficient, but... you need to push all of that water around, making sure you can cool it before it makes the return trip.

The primary concern of owning a water-cooled system is maintaining all of the seals in the presence of a fair amount of water being pushed through the tubes by the water pump. There is a great deal of mechanical work being performed as the water is circulated. If you think this might be a bit of an exaggeration, walk to your local grocery store and carry home 2 gallons of water, then take a trip around your block with them for good measure. The pump is pushing more than this volume through its tubular causeway every couple of minutes.



Enter the Peltier cooling solution. Shown above are aluminum and copper heat sinks fitted together with Peltier junctions to form two central "bricks". Once wired as shown, the junctions will pull heat from the center bars outward. The middle portion gets frosted and the outtermost section is too hot to touch. How exactly does this work?



In 1834, a French physicist named Jean-Charles Peltier discovered that an electrical current at the junction of two different metals will produce a heat gradient across the materials. When you pass current through a closed circuit including the metal junctions, heat is evolved at the positive junction and absorbed at the negative junction. The heat which is absorbed by the negative junction per unit time, is given by the equation above. Of course, I is the measure of current. The pi terms denote the Peltier coefficient of the combined thermocouple (AB) and the Peltier coefficients of each material separately (A and B).

The Peltier coefficients represent how much "heat current" is carried per unit of charge through the various substrates (and the combined thermocouple). Because of the fact that the charge current must be continuous across any junction, different materials (with different Peltier coefficients) will produce a discontinuity in the heat flow. This results in a non-zero divergence at the junction, so heat must either accumulate or deplete depending on the direction of the flow of charge (the "sign" of the current). This effect can be amplified by placing thermocouples in series.

So, in short, a Peltier device can act as a thermoelectric cooler, greatly reducing the amount of heat that would otherwise need to be carried away by a relatively large mass of water. With some experimentation, overclocking enthusiasts will no doubt discover the ease associated with building cooler systems with fewer moving parts (and worries).