But as of now, the thermal difference is insane.
I've only had this laptop for 3 days, so what 'stable' looks like can change as I use it more. I now get thermals between 65-72C while playing Fortnite, and idle temperatures of 38-42C. I also used this to disable Turbo Boost to avoid the 88-91C temperature spikes and thermal throttling. Using Intel's XTU tuner, I was able to run a benchmark and play a few games (stable) at a -140mV undervolt. This is well above the safe operating temperature for continued and lasting performance from a CPU. This was done using the voltage control on MSI Afterburner. 2019 GS65 Stealth (I think it might be the 666 or 667 model) i9-9880H 32GB Ram RTX 2080 Max-Q Description of problem: CPU Core temperatures easily exceed 90 degrees C and can regularly hit and maintain 95C. I was able to sustain a stable undervolt down to 912mV (from just over 1V) which allowed me to run Fortnite at 120FPS (I capped it here because I personally can't see the difference between 120FPS and above) with max AA and textures (no shadows) at 65-68C with a moderate fan curve (65%ish at medium to medium-high temperatures). Remember that YMMV in this silicon lottery, but it should help provide guidelines on where your settings should fall. I have spent several hours tinkering with undervolting and fan speeds trying to find a good temperature range for the GPU and CPU to operate at while gaming WITHOUT a cooling pad or liquid metal repasting.