Now I have purchased and packed on the radiator of my WaKü after long deliberation 2 of this fan. Lo and behold, only 62C ° and my CPU Bitches (beep) is no longer the be it her warm. (And I've accustomed myself sooo :))
The fans run at 600-2300 RPM now and then with 2890 RPM.
On Max. Speed they are very well audible, but considering that they again it is acceptable by pulling air to the 260 cubic meters.
Therefore agree with the previous. Strong buy recommendation.