Can't set case fan speed below 60%

I got a CM JetFlo 120mm case fan and a Asus M5A97 R2.0 motherboard.
I plugged the case fan into motherboard's cha_fan1 connector and use it as a exhaust fan.
Problem is that it's always spinning at 60% speed and is very loud while unnecessary, because I am not in games.
In UEFI I can't set the value of chassis min. duty fan speed below 60%, it only allows 60%-100% value. Same goes to maximum fan speed.
While gaming 60% is ok but not while I am watching movies or browsing internet, it's really annoying. Before I installed the case fan I could barely hear my PC now it sounds like a jet.

How do I lower the fan speed?

 

Check out Speed Fan it is free and does a real good job.

Thermalake also has a multi fan controller.

 

I really don't like SpeedFan, it's really confusing and I don't think that it even shows my case fans.