So I'm having an opposite problem than a previous thread: when I power up the board, the fan slowly ramps up to full power and stays there permanently. According to lm-sensors the core temperatures are only around 30-40 C, which are well below the AC0/1 limits I've set in the BIOS. I've tried a couple of different fans, disabling the BIOS temperature limits and re-flashing 1.03 but nothing seems to work. Any ideas? I wonder if the BIOS is somehow using an incorrect temperature/threshold because the slow ramp-up to full RPM only happens if the board has been off for some time; if I turn it off and on without letting it cool, the fan immediately goes to full throttle.
I can't recall if the fan is two wire, or three wire? It seems like the sense wire is not making contact to the main board, and therefore the CPU cannot detect fan speed (if 3 wire)?
Update: I double-checked all the connections, reset BIOS settings and tried a couple of other fans but just couldn't get the BIOS speed control to work. In the end I resorted to writing a small program for the Arduino that drives the fan directly and a host-side binary that controls the former through the serial port based on the measured core temperatures. Let me know if you're interested in more details.
