Thermal Performance

Everything needed—monitor, peripherals, motherboard w/CPU and GPU, radiator, PSU, and so forth—is placed in a sealed, climate-controlled box at 25°C +/- 0.05 °C. Each radiator is connected by Koolance QD3 quick disconnects for easier changing of the fans and radiator. The flow rate is held at 1 GPM constant flow rate. The CPU, an Intel Core i7-4770K at 4.6 GHz and 1.3 V, is held at a constant load using a custom Intel XTU profile, and the GPU, an EVGA GTX 780 Ti Classified under load from Unigine Heaven 4.0 at 1080p with extreme HD settings, is overclocked and overvolted in such a way that the total system power draw is 550 W as measured by a power meter.

A near-constant heat load into the liquid loop by the addition of the CPU and GPU helps quickly achieve stable liquid-loop temperatures as measured by three separate in-line temperature sensors hooked up to an Aquacomputer Aquaero 6 XT. The tubing and fittings are insulated by a sleeve heater, but its heat function is not utilized. Every single measurement is done twice as a means of verification. Any possibility of running a fan outside of its static maximum RPM is minimized by as much as possible by using a comprehensive series of separate fans (Noiseblocker eLoop, B12-1 through B12-4) to cover a broad RPM range while minimizing fan speed variance and, thus, airflow. The results below are the ∆T (coolant temperature - ambient temperature) in degrees Celsius.


Keep in mind that the current test database does not include many other radiators, with most radiators I have tested before being 480 or 560 mm. I have also subsequently gone ahead and removed the 2200 RPM results here because the trend is clearly against much higher speed fans, especially as there are now better performance/noise fans than the NB-eLoops used here. That said, color me impressed! Watercool says it was targeting the new radiators for good low-to-medium speed performance, and perhaps the lower end was potentially hampered by the louvered fins here. But the fin and core geometry helps with medium fan speeds—I will again note that you can get equivalent performance at lower fan speeds with better fans. The thicker Heatkiller 360-L scales better with airflow too, even to where it currently takes the top spot, but only just, in the medium fan speed regime. Nicely done, Watercool!