Noctua's fans are really high quality, from the packaging to the accessories and the fan itself. Mounted fan right becomes almost silent, but for me it was a problem.
I have a Fractal Design Define R 4, where one can mount the fans by pushing them in front, which is removable. It screws thus not fixed them without tryckår them. The problem is that the rubber that sits on the edges do not go in properly; you must remove the rubber on the front, however, the rubber on the back to sit still when pressing extra hard to get into it. The fact that you have to remove these rubber pieces allows the fan vibrates.
In other words, it is best to use this fan by screwing the right things, otherwise you have to be prepared to cut down significantly speed to avoid noise.
The problem with this, however, the look - you do not like putting it in a place where people can see it. Brown & Tan must be the ugliest combination. This limits the fan can sit, if you care about this.
You must attach the fan in the front, as in the Define R4, buy another fan. Can you skuva fixed it correctly, this is however a top fan.