A phase change cooling system like the Prometeia Mach II GT essentially works like this: the compressor pressurizes a gaseous refrigerant into liquid form, which causes it to rise in temperature. The liquid refrigerant is sent to the condenser (a heat exchanger) where it is cooled down.

The liquid refrigerant is then forced at high pressure through copper capillary tubing into an evaporation chamber, which is a low pressure area. There it evaporates (changes from from liquid to gas) back into gaseous form and absorbs latent heat in an endothermic reaction. The now heated gas is then pumped back into the compressor to be turned into a liquid before proceeding to the condenser again to dump its heat.

The evaporation chamber in a phase-change cooling system like the Prometeia Mach II GT happens to be the block of copper which is attached to the CPU. As the chamber decreases in temperature, it absorbs the heat energy from the processor below it, lowering the chip's overall temperature as well.

Acoustics, fans, pumps, and just how loud is a phase change cooler?

Despite what you may assume, a phase change cooler which comprises of a refrigerator-style compressor and pair of DC cooling fans, is not loud. When the Prometeia Mach II GT is first turned on, the compressor runs at full load (which produces up to 41dB of noise according to ECT) until the cooling head reaches its booting temperature. Once the head hits this temperature mark the system switches to normal operation mode (35dB) and the fans run at about 50% speed.

The Prometeia Mach II GT can connect directly to your computer via USB, so can also adjust the speed of the front and rear fans to increase/decrease the noise level further still. The compressor generates a low pitched hum that anyone in the western hemisphere is familiar with, and so it blends nicely into the background.

Overall, you will have a noticeably louder system with a phase change cooler running than you would with a stock heatsink. On the other hand, it will be much quieter than any mid-level overclocking fan on the market.