I do have my fans connected to the fan header with such a 3er y splitter. After browsing and trying around a lot in bios and various tools, I found a setup that seems to work for me. Changed in bios to voltage mode and I was able to change the rpm/temp curve in Easy Tune. The cpu fan took the changes and runs now at the levels that I wanted him to :) At first I thought these settings would only apply in pwm mode, but as it seems they also work with voltage fan control.

Thx 4 the all the help :)