Hello,
Assuming you still have the problem, I have just found the solution. I have a very similar machine, HP pavilion Gaming having i7 9750H, GTX1660 Ti, and had the same problem for quite some time, which also began after updating my drivers. The CPU would always be running inTurbo mode, aroung 4GHz, and running at 80 - 85 C when connected to supply, otherwise running very cool, around 45 C on battery.
I used to blame the GPU for removing the power limit when connected but it turns out there is an issue with the power management in windows. In Ubuntu 18.0.04 the temperatures used to be fine, around 55 C.
As written in one of the above replies, changing the CPU state will be effective, but there is a caveat, the power state controls the p - states (roughly frequency levels) for all configuration modes, except the power Supply Connected with the slider on "best performance" in the battery indicator.
i.e. For the laptop
1) running on battery and slider anyway between Best Battery Life and Best Performance,
2) and, for the laptop connected to supply for the slider at "Best Battery Life" and the intermediate levels,
the processor will not go to the Turbo Frequencies and any changes applied to power states in "Advanced Power Settings" will be visible.
For the last case of Supply connected and Best Performance, the battery states, (minimum or maximum), have no effect and the processor stays at the maximum possible frequencies, even with no load.
Also note that the power states are p-states (
1) (
2), and not exactly the frequencies, so the maximum and minimum frequencies will change in steps (multiplier and FSB (
3), and we will not get all 100 values. Similarly, the 0% would be the lowest state, which is around 800 Mhz for us I think.
Thanking You