That resulted in a -10C average CPU temperature. Massive!
I don't remember last time I heard the fans. Not even with Docker + Jetbrains IDEs.
I wonder why doesn't it come like this by default. It runs faster too because it's no longer frequently thermal throttled.
Because pumping up the voltage also allows them to increase the base clock frequency without causing instability. Consumers learned to compare the frequencies during the CPU wars so that's what they juice for marketing purposes.
Newer Thinkpads are notorious for this. Many of them can operate fanless 99% of the time if they just undervolted them by 100mV like you did. It's the first thing I do with a new laptop after installing a clean OS.