Classic hardware: The Prometeia Mach 2

Do you think a large air cooler able to keep a high-end CPU below 50 degrees Celsius under load is extreme?

What about a custom water cooling loop that works hard to keep the same CPU just a few degree above the ambient temperature?

You don’t? Well what about a phase change cooling unit that can reach negative 65 degrees Celsius; one that keeps your CPU under zer0 degrees even with 100% load? That is extreme.

That ladies and gentlemen, is the Prometeia Mach 2.

A brief history lesson

The Prometeia Mach 2, introduced back in 2003, was made by a Dutch refrigeration company called Elcold Frysere Hobro APS, who have been in the cooling business since 1961, though for the most part dealt with industrial and personal cooling solutions.

The Mach 2 retailed for around US$950 in 2004 and was sold in low volumes thanks to its high cost, tricky install procedure and small target community (overclockers).

Adding to this, the Mach 2 faced stiff competition from the likes of the Vapochill LS, a competing unit which could in some scenarios get colder, though at the cost of temperature stability.

What made the target market even smaller was the rapidly expanding dry ice and liquid nitrogen market which saw overclockers make use of these temporary solutions to reach lower temperatures. The Mach 2 and Vapochill LS also faced competition from private builders who could provide more powerful custom built systems, though at a higher price.

The front panel loading screen

An introduction to phase change cooling

Phase change cooling in a PC is very similar to how an air conditioner works. It involves a compressor which compresses gas until it turns to liquid. The liquid is then pumped up to the head of the unit which is installed into the CPU.

The liquid runs through capillary tubing which expands it, until it reaches the unit head, where the liquid evaporates (changing phase from liquid to gas). The liquid changing phase absorbs the heat from the CPU as it draws energy from the environment to accommodate the change in phase. See this Wikipedia article for more info on latent heat.

The gas then flows back down to the compressor and starts the process again.

Prometeia internal cabling

Issues with phase change cooling

Phase change cooling is slightly more extreme than air or water, and brings with it a few “extreme” problems. Due to the incredibly low temperatures at which the unit operates, insulation is required at various stages of the unit.

The pipe leading to the CPU needs to be insulated to avoid sweating (where water condenses on the pipes).

The CPU socket by the head of the phase change cooler needs insulation to prevent nearby components frosting up, and most enthusiasts will advise covering the entire board around the CPU in either dielectric grease or Vaseline.

The rear of the board also needs a coat of Vaseline and a layer or insulation between the board and the backplate that holds the cooling head onto the board.

Prometeia cooling head

Customisability

Another aspect of the Mach 2’s appeal was that overclockers could customise it.

Easy modifications included replacing the standard refrigeration gas used in the unit (134a) with R404a or 507 gasses that changes the characteristics of the cooling for lower temperatures, better load or greater stability.

Another modification was to change the evaporator, or “head”, of the unit that made contact with the CPU, also to improve stability and temperature.

Advanced modifications included replacing the capillary tubing used to expand the gas, or even swapping out the compressor unit in favour of one more powerful.

Prometeia frosted head

The end of a legend

As newer, more powerful methods of cooling rose to popularity, demand for the older phase change units dropped considerably. The already small market shrank further until demand for the units ceased and local distributors closed down.

Rare, unique, expensive, extreme; the Prometeia Mach 2 is a standout piece of classic PC hardware, and demonstrates the lengths enthusiasts will go to for the ultimate system.