Here's another cool thing to come out of Computex this year: a closed-loop liquid cooler from Raijintek that is entirely passive. The company's latest design doesn't require a pump to push coolant around the tubing, and there are no fans on the included radiator.
This liquid cooler harnesses the same technology as heat pipes, and uses phase changes to transfer heat away from a hot CPU. Essentially, the coolant within the tubes phase changes from liquid to vapor at the hot CPU block, consuming heat energy from the CPU. The vapor then travels to the radiator where it condenses back to liquid and returns to the CPU block to cool it once more.
It should be noted that the liquid inside this closed-loop cooler is very different to a standard closed-loop cooler. For the phase change system to work effectively, the liquid must have a low boiling point so that it vaporizes around the temperature of a stressed CPU. Most of Raijintek's research and development budget would have gone in to creating this special fluid.
According to TechPowerUp, Raijintek has patented this technology and will be bringing it to market soon. Unfortunately we don't have any performance data yet, so it's hard to know just how effective it is at cooling CPUs, although TechPowerUp did say that the closed-loop cooler being demonstrated worked.
If an effective pump-less closed-loop liquid cooler is brought to market by Raijintek, it could be a great option for silent PC enthusiasts who want decent cooling without the noise of a pump or fan.