I made following adjustments:
- Upgraded RouterOS from long-term to stable & updated Firmware to match
- Reduced CPU clock from 650 MHz to 550 MHz
- Disabled all SFP interfaces
Now the fans are running between 0 or 4k RPM in the following pattern (pink is CPU temp [56-61], blue is FAN rotation speed [0-4000]):
Not sure if those constant turning off and on wont break them in the long run. What are your experiences with this device and temperature/loudness?