Ok, i have an update:
the fans of the psu's are quieter than before the efi-update.
The fans of the chassis are still most the time at 100% but sometimes (during the startprocess) they were quieter. This leads me to think that in principle the fans can be throtteled. Now im searching for a method how i can do this.
By the way i think eve if 'pwmconfig says that there are no pwm-sensors, the technical pruduct specification says that on every fan-pin-out there is this:
"Pin ..... | fan PWM | Out | FAN_PWM signal to control fan speed"
If this isnt a pwm-sensor correct me please.
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We regret to inform you that the board you are looking assistance for is end of interactive support (EOIS) reason why we recommend checking our website for further information:
Intel® Server Board S5520HC
As an additional recommendation, if the firmware update did not address the issue properly you can run the Intel System Information Retrieval Utility (sysinfo) For UEFI to check the server system logs and review them.