re-enable the BMC via jumper and it should be auto-controlled by the BMC, and possibly overridden via IMPI
thanks for your answer, but I tried everything except reenabling the BMC for privacy and security reasons.
And (tested) the IMPI of the mainboard (X10SDV-8C-TLN4F) does NOT override the BMC. The fan control only goes thru the BMC (see also the docs and forum from supermicro). So I had to install in the rack a Corsair Controller Pro (cooling controller) to control the cpu fan without the BMC.
IMPI is the interface to the BMC, it’s not functional if the BMC is disabled via jumper