antho: downvolt them. From experience of many owners of GTs, they are very silent at 1000-1100 rpm, and for many others they are silent enough even at 1450. You'll also have performance reserve for hot days for full speed of 1850 (which some told that is still comparable to noiseblocker's 1400).

davidm71: I'm pretty shure that at 1300 those noctuas might outperform GTs flow wise .. but if they are already making same noise at 900 as GTs at 1400, they most probably will be anything but silent at 1300 . Imho rpms are almost always completely irrevelant in fan to fan comparison. Depending on fan blade count and profile, engine size and alikes different fans give different noise, different flow and different pressure at same rpms. So only thing that really matters - flow vs noise. As in which blows more at particular noise level or which is most silent yet blows enough. Pitty many manufacturers game with specs to sell their (sometimes inferrior) products. Like reporting noise for minimal rpms, telling performance at maximum, never mentioning distance how far from fan microphone is placed, never comparing with top fans but often with their previous ones or some clearly inferrior ones, rarely using special sound proofed accoustic chambers. At the end, only way to make more-less objective choice/comparison are independent 3rd party tests. Hopefully with competent testing methodology.