[coreboot] Issue with BMC module

[Ale]

Hello everyone,
I have a kgpe d16 motherboard with coreboot and seabios, for now I have only one CPU mounted (the 2nd socket is empty) with 64 gb of ram: if I power on the PC without the BMC module, fans will spin at the maximum speed and I can see seabios and boot the OS; if I put in the BMC module with openBMC installed then fans spin at lower RPM but the seabios is not shown anymore (and, therefor, the pc cannot boot the OS).
Do you have some idea of why this happens? Maybe I need 2 processor for openBMC to work fine?

Thank you very much!
Best regards
Alessio