"when they announced the NH-D15 to us we immediately knew that it would be a worthy successor to the highly acclaimed NH-D14. Sure we didn't expect miracles since in their current state dual tower CPU Coolers have pretty much reached their maximum cooling efficiency but we did expect something more from Noctua and so surpassing the Silver Arrow Extreme by Thermalright was a very pleasant surprise. Noise levels play a significant role in the end game and so having the best possible cooling efficiency (it did dominate the chart) with relatively low noise levels is always the best possible scenario thus the NH-D15 has placed Noctua back at the top of CPU Air Coolers"
NikkTech.
Noctua NH-D15 review by NikkTech - Introduction & Conclusion.
