i have an i5 3570k at stock with an arctic cooler 7 pro rev2 aftermarket cooler on it. When gaming the temperature seems to stay under 50-60° which is fine? But the fanspeed is only around 850rpm while idle en 1300 while gaming. I've heard thats kinda slow. Any ideas?
yes. You made the mistake of buying a good fan. Artic specializes in low noise systems, and that means fans that run slowly. If you miss the screeching whine of a loud fan though you can always pick up a piece of constant speed sleeved crap from the bargain basket at microcenter and throw it in.
Personally i clock down my fans to keep them below 1000 rpm at all times. it makes for a more pleasant living environment.