I recently came across an issue with a new HP EliteBook 840G6 Laptop and USB-C Dock. After connecting the dock the CPU fan RPM increased
Windows, Driver, firmware and BIOS were all up-to-date.
Disabling Turbo-boost in the laptop BIOS resolved the issue and CPU Fan noise remained normal when dock was connected
- Boot to the laptop BIOS
- Navigate to Advanced Settings
- Disable Turbo-Boost
- Reboot laptop, connect dock and CPU Fan RPM should remain at normal levels

My HP Pavilion Laptop which is 14 months old doesn’t have “Turbo-boost” in the BIOS settings. My model number is 15-cs0064st and the BIOS is V.06.