Motherboard fan control not working

[Andrew Doenges]

I have my fans plugged into the sys fan ports on my mobo and no matter what they are always at %100 rpm and I cant seem to get them to go slower. Any ideas?

Case: Corsair Air 540 stock fans + corsair 3pin 1200 rpm fans
mobo: msi b85m g43

 

[alexoiu]

The board has 2 x 4-pin system fan connectors. It seems that it is not able to control 3 pin fans (I couldn't find a setting in BIOS, checking the manual). An option would be a fan controller.

 

[clutchc]

+1^
If you are using 3 wire fans on a 4 wire (PWM) header, the MB BIOS won't be able to control their speed. Because the BIOS is using Pulse Width Modulation to control speed when there is a 4 wire system, not the older variable voltage. You need PWM 4 wire fans to control the speed with the BIOS. Or you could buy a 3 wire fan controller and use that instead.