I don't think a threshold of 0 works with Supermicro boards. When I had an ASRock board I could set it to 0 and actually turn the fans off. On my Supermicro I have the ipmi thresholds set to 200 or 300 and set the fan control minimum to keep the fans above that. Fans randomly spinning up to full speed is usually a symptom of incorrect threshold and minimum settings.
I had already experimented a bit with the threshold values before. If all 3 values are below the minimum revolution it seems to work ok, but today I noticed an unexplainable revolution increase of all fans.
I have now set the lower thresholds to 100 200 300. I'm surprised that the fans run close to their minimum revolutions despite the minimum set to 30%. Or did I misunderstand the percentage setting? The fans should then run at 30% of their RPM range, right? According to the log, the fans also run at the corresponding percentage values