This article was written by Steve Burke from GamersNexus
Closed-loop liquid coolers are growing more popular for CPU and graphics cooling in the gaming market, and part of that is attributable to their easy installation and high performance. Still, liquid coolers inherently have more points of failure than an air cooler – it’s just a matter of whether manufacturers work to include quality components that permit the cooler to live a long service life.
The coolant inside of a liquid cooler is a mixture of propylene glycol and distilled water, with the split of these depending on what environment the manufacturer expects the cooler to occupy. This mixture doesn’t “evaporate,” per se, but does slowly permeate the tubes containing the cooler. This is why cooler manufacturers (like NZXT) often make a big deal of the research going into the tubing material, as that material is what sits between a long-lasting cooler and one which slowly loses its coolant to permeation. NZXT’s 6-year warranty largely speaks for itself, and reinforces that the Kraken series is designed for long service life.
Some closed loops are more easily refilled than others, but with the right tube material and with controlled liquid temperature, users shouldn’t have to refill their loops (within the usable service life of the system, especially). The Kraken series of coolers uses a permeation-resistant rubber tubing with a pump that adjusts its RPM (via PWM) based on liquid temperature. Liquid temperature is ascertained through thermocouples embedded within the pump block: If the thermocouple detects temperature rise, the pump RPM will increase to help account for this. Of course, Kraken coolers also include software that allows the user to write their own pump behavior, just like a fan curve profile. As long as liquid temperature remains below 60C, the cooler will remain healthy and permeation will be minimized. In some testing, NZXT Kraken X62 coolant temperature remains close to 30-35C even when under the intense heat load of an overclocked i7-7740X. High pump RPM and PWM fans are largely to thank for this feat.
Using software like NZXT CAM will report the coolant temperature, if the curiosity ever arises, and helps to understand performance under load. If coolant temperature begins to rise – though the default profiles should take care of things – it might be worth ramping into a more aggressive pump/fan RPM. Again, the coolant won’t evaporate from the tubes, but excessively high heat loads can cause permeation. Pumps will suck air through the system as liquid volume decreases, eventually causing “gurgling” noises as air bubbles move around.
To reduce the risk of permeation, we recommend the following tips:
• Download & install the NZXT CAM software to check liquid temperature and pump speed
• Install CLCs with the tubes at the bottom of the radiator (if vertically oriented, e.g. front-mount)
• Avoid installing CLCs flat in the case, with tubes facing upward
• Keep coolant temperature below 60C – this normally isn’t a problem, but excessive ambient environments & hot cases might make it worthwhile to set a custom fan & pump curve