Noctua NF-S12-1200, 120mm

I did this review in English, if you don't mind, because my Dutch is not that great and it would have taken me ages to finish this review.
About a month ago I bought the Cooler Master Cosmos 1000, which came with 4 12cm ventilators. These ventilators were supposed to be quiet (17dB) but when I connected them to 12V I could hear ticking noises and just noise in general. When I tried connecting them to 5V, the noise production was ok, but they were just not pulling enough air to cool my computer. My hard drives were warm (41 C) and the processor, when fully loaded, was at 57C. You could see the effect of the slow pulling power when letting the processor come back to idle. It took it more than a minute to come back to its base temperature (37 C).
For this reason I decided to buy some new fans. I looked around on Tweakers and saw that everybody was looking at the Noctua fans. So, after contemplating for a while over the price, I decided to buy them. So, 4 fans and 67 euros later, I was the happy owner.
First thing you notice when you get the fans is their unusual design. I kind of like it. The second this is the rubber noise cancelling plugs. I had no clue how to connect the fans with the noise cancelling plugs and because...