Thank you for your answers!
But I have solved the problem:
Yesterday evening if have moved the cmos battery and turned the pc off at the back-side. TOday morning I have put the battery to the mainboard and turned the pc on.
During the init-time (when the intel-splash is shown) I've heard my fan again, but then, when my grub was displayed (bootloader), everything was silent :-)
Now I have turned on my pc and the pc fan did not rotate at maximum.
I'm so happy and hope, that this state of the cpu-fan-control is stable now.