The new noisemagic cpu cooler arrived today. It is worth the 55 euros - I had to double check that the fan is really running since the fan hardly makes a noise. The downside is that the mainboard gets really hot. According to BIOS somewhere around 45 degrees.
Should have bought it a lot earlier. I’ve also ordered a noisevibe harddisk mounting frame with a cooler to reduce the temperature of the server’s harddrives.