The Cooling System
The cooling system was designed hand in hand with the case, with the size and location of all the components considered from the outset.
The system departs from the usual in-line cooling loop by using dedicated coolant lines from the radiator that run directly to each of the processors. This entailed making two outputs from the radiator instead of one, but three were made, just in case there would be additional components cooled later. The lines are split at the CPU blocks, but instead of going through the usual ‘Y’ connector, they merge at a machined and anodized aluminum manifold. From there, coolant returns to the Eheim pump through a single line and then back to the radiator.
To avoid having any of the radiator’s air entering the case itself, it is located in the rear where the airflow can cross right through the enclosure. This meant fabricating a custom built radiator from an automotive style heater core, a special offset fan shroud and custom hose fittings adapted to the radiator tank were in order.
I turned to the master of custom PC radiators, Keith (DodgeViper) Thompson, to build a complete radiator and shroud. He started with a standard heater core, but as you can see from the pictures, he modified it extensively. First, it was fitted with a Â½’ NPT inlet fitting and three Â¼’ NPT outlet fittings. The off set shroud was fabricated out of brass flat stock and has nuts, for mounting a 120mm fan, soldered in place. The base of the radiator even has mounting nuts soldered in place.
These photographs speak to Keith’s attention to detail and fabricating skills.
This shows how carefully he made the shroud offset fit perfectly, by cutting a wood buck to the proper dimensions and ‘wrapping’ it with brass sheet stock before soldering the unit together.
A manifold takes coolant to a single Â½’ NPT outlet fitted with a 5/8′ barb, from four Â¼’ NPT inlets with Â½’ barbs. These four are return lines from the CPU’s, while a fifth (not seen in this picture) is used for the air trap. The manifold itself is machined and anodized aluminum, purchased as a standard item from McMaster Carr. The hose barbs are all stainless steel, purchased from auctions on eBay.
To circulate the coolant, an Eheim 1250 pump was selected. It is mounted directly to the case’s base plate with a vibration dampening base, next to the radiator. The damper is essentially a sandwich of a fiber reinforced rubber pad and a secondary Â¼’ thick aluminum plate.
The water blocks for the CPU’s are these acrylic topped RBX units from Danger Den. The design and fabrication of these blocks is quite impressive. As we’ll see later, they perform just as well as they look.
With the mainboard mounted in the case and the entire cooling system assembled in the shop, it was powered up and tested for leaks. There was indeed a small leak in the radiator. I’m certain it happened while tightening one of the barbs. It was easily fixed, but a good example of why it’s important to test a liquid cooling system before installing other components.
The cooling system ran for a few days before work on the rig went further.