CoolIT Freezone CPU Cooler (LGA775)

Verdict: Brings together a thermo-electric cooler and water-what could go wrong?

The Freezone is the first retail product from CoolIT, but the company has been producing high-end cooling systems for Voodoo PC and SavRow for several years. In fact, if you look closely, you'll see a striking similarity between the Freezone and the cooling system in the winner of our 2004 Dream PC competition, the SavRow Deuterium.

The Freezone isn't a standard water-cooling system, although the basics are the same. In a standard water-cooling system, the coolant is heated up as it passes through the CPU waterblock, and then cooled as it passes through a radiator, which is in turn cooled by one or more fans. Instead of a radiator, the Freezone uses a heatsink. The system pumps coolant through a CPU block, and then through a bank of three low-power Thermo-Electric Coolers (TECs), which transfer the heat from the coolant into a large copper heatsink. The coolant is then recirculated by the pump through another bank of three identical TECs before returning to the CPU block. The heat transferred into the heatsink is then removed by a variable-speed 92mm fan.

In theory, the Freezone should be more effective than a standard water-cooling kit since the TECs are more effective than a standard radiator at conducting heat out of coolant. While a radiator is just a large, hollow heatsink, TECs exploit the Peltier effect, whereby passing an electric current through two dissimilar semiconductors causes heat to transfer from one to the other. Some other high-end water-cooling systems also feature TECs, but these are usually mounted between the CPU and waterblock, not on the heatsink, as in the Freezone. This design means that the Freezone has space for several low-power TECs, rather than one turbo-charged TEC, so it doesn't require a special, separate TEC PSU.

The Freezone is easy to install, as it's shipped fully assembled and pre-filled. All you have to do is attach the small block to the top of your CPU and screw the pump/heatsink/fan/TEC unit to an exhaust fan mount on your case. As the heatsink and fan are both 92mm wide, an adaptor is provided to mount the unit on cases with a 120mm fan mount. The fan speed and power input to the TECs are controlled by a small PCB, which is powered by a single Molex connector. A standard 3-pin fan cable powers the pump. As standard, the Freezone automatically regulates the fan speed and power level of the TECs according to the CPU temperature, but you can also manually adjust the settings via a small rheostat on the control PCB. The coolant inside the pre-filled tubing is a mixture of polypropylene glycol and distilled water, so it's immune to algae growth and shouldn't need replacing.

Mounting kits are supplied for attaching the block to Socket 478 and LGA775 Intel CPUs, plus all socket types of Athlon 64 processors. For LGA775 systems, you'll need to remove the motherboard from the case to fit a double-sided retention mechanism, but for Athlon 64 systems, the standoffs simply screw into the CPU mounting bracket.

Everything was looking rosy for the Freezone until we started to get the first set of temperature test results from it. In our LGA775 test rig, the overclocked and overvolted Pentium 4 was cooled to 13ûC below the reference Intel HSF with the fan at maximum power, and just 6ûC below at minimum power. At maximum power, the fan is almost as noisy as the reference Intel HSF, but many HSFs, such as the Arctic Cooling Freezer 7 Pro, provide better cooling while being much quieter. High-end water-cooling kits such as the Swiftech H20-Apex Ultra are even better, in this case, cooling the same CPU to 26ûC below the reference Intel HSF.

The Freezone is better at cooling Athlon 64s, but that's hardly surprising, as our test chip has a lower TDP than our LGA775 test CPU. At maximum TEC power, the overclocked and overvolted Athlon 64 FX-55 was cooled to 19ûC below the reference AMD HSF, but ran 1ûC hotter at minimum power. However, 19ûC can be matched by some high-end HSFs, and is also bettered by the Swiftech kit.

CONCLUSION

The fundamental limit of any liquid-cooling system is how quickly it can dissipate heat from the coolant, a process that we've found is best achieved by using as big a radiator as possible. So although the use of TECs to conduct heat into the heatsink in the Freezone is innovative, it doesn't solve the problem of moving the heat outside of your PC's case. Regardless of how effectively the Freezone conducts heat out of the coolant, the heatsink and fan aren't large enough to dissipate the heat out of the system. A redesigned system with a 120mm or dual 120mm-fan heatsink could make the Freezone a powerful cooling system but, in its current configuration, the Freezone's performance can be matched by cheaper HSFs, and exceeded by high-end water-cooling kits.