Should add - I am trying to control the fan speed by adjusting the minimum and max fan speed % in the BIOS, not by a 3rd party app through the OS. When a non-PWM fan is connected to the CPU fan header, it is always at 100% speed regardless of what % minimum and maximum speed I enter for the header.
I think I have the exact same problem, tryed all the software if could find, both Intels own and SpeedFan, none of them are able to control the fan, even tho they appear to be.
Trying setting the max duty in the bios but nothing happens, can't find any info in the manuals on this any where!
I think I will switch to one of the aux fan headers (Red ones) aswell, but its kinda annoying!