I think something's wrong with my monitoring cause it shows that my AMD FX 4100 stock cooler is spinning ith over 4000 RPS !! Since I've been advised by some of you to buy an afermarket cooler I was trying to find a good one and I didn't saw not even one with max speed over 2500 RPS ... ???????
The RPS isn't important unless you mind the noise.
A fan with bigger blades needs less RPS for the same volume of air pushed/pulled than a smaller fan and the design of both the blades and the fan also matter.
Aftermarket coolers are way better than stock ones no matter the RPS