Fixing Thermal Throttling on Thinkpad P1 and X1 Extreme - Linux Edition
Lenovo messed up with the X1E and P1 Gen 1 versions (and maybe later generations) in that the system boots with a thermal limit (aka Tjunction or tjmax) set to 82C (some report 80C). What this means is that regardless of power draw or under-volting settings, when your CPU hits 82C, it will drop the frequency down to the "Configurable TDP-down" frequency, or even lower. It will also may limits the system power draw.