Furthermore: The imaginary for decoupling, enclosed rubber pads between the cooling block and the fans are after not where the fans really rests, directed to follow the instructions of the manual. I have completely removed, cut and repositioned (left and right, at the edges of the cooling block). The fan itself can be on the rotor blades poorly trimmed, was the case at least for me, I have also worked again with the file.
Overall, most of the time the fan PWM controlled runs with me at about 550 RPM. He is not audible to me. For the price a good acquisition.
Edit December 2013: Have been an AMD FX 8350 Octa-core processor running at this cooler. With Arctic Cooling MX2 thermal compound and it is not hotter than 50 ° C, with three case fans (2x 120mm 1x140mm) in unchanged Case (Fractal R4) ensure passage.