The reason the CPU fan is working harder is the CPU is now working rather than loafing along on one processor.
Yes, that's now also my impression. Fan control definitely works. I will play with the ACPID.CFG settings the next days.
Anyway, I'm now quite happy with my new board (ASUS B350M-A) Besides SNAP (of course) all seems to work now. Only the installation was not so easy.
Two simple batch files which have to run not in the OS which has to be changed would be useful. I don't know now if the installation problem (need to use "modern hardware, safe mode") is because of the old 3.23.08 version or because it does not work when installing even 3.23.09 is installed.
Anyway, I think a default base install with a more comfortable post-install program (or simple batch files) would be useful. Even Windows 10 only installs a base support and you have to post-install chipset drivers and graphic card support.