Dell E7440 fan does not throttle

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Hi There,

never posted at a forum like this but I need help. I have a Dell E7440 with Fedora 25 on it and the fan does not throttle down. The output form lmsensors lists:

[$] sensors
coretemp-isa-0000
Adapter: ISA adapter
Physical id 0:  +53.0°C  (high = +100.0°C, crit = +100.0°C)
Core 0:         +52.0°C  (high = +100.0°C, crit = +100.0°C)
Core 1:         +53.0°C  (high = +100.0°C, crit = +100.0°C)

acpitz-virtual-0
Adapter: Virtual device
temp1:        +25.0°C  (crit = +107.0°C)

dell_smm-virtual-0
Adapter: Virtual device
Processor Fan: 6687 RPM
CPU:            +52.0°C  
Ambient:        +42.0°C  
SODIMM:         +43.0°C

It is silent when the notebook starts. It turns up correctly when there is higher load. But when the load decreases it does not throttle down until the sensor dellssmvirutal-0 CPU is below +50.0°C. I have read that there is the i8k module and utils to do that manually, but not in f25 anymore.

Question: How do I get my notebook silent?