At the time, I ran a CPU stress test which put all cores at full load for a couple of hours.

Then I ran RAM tests.

Then I ran NVMe stress tests.

Then I ran GPU stress tests (NVIDIA GPU is underclocked).

Then I ran all of these tests together.

Worked butter smooth. Not a crash to this day.

To be fair, -100mV is on the safe side according to the articles I read at the time. Some folks run at -200mV or less. I don't need that kind of tweak.