"Compared to the models that Noctua succeeded with (as mentioned in on the very front of the box), there are gains. The Flow Accelerations Channels are the real difference here and are likely the reason for the improvements. However, these improvements are not across the board. These fans use more power (still barely enough to even blink at though) and are slightly to a fair bit louder. However, they have higher RPMs, better CFM, and much better static pressure ratings. This still easily constitutes an improvement in my book and simply exemplifies the difficulties present in trying to reduce noise while improving performance.”



Link: OCC