This, x100. Most people would know of overclocking but not undervolting, with the irony being that the latter can be far more useful for the average user.

For example, I have a stock air cooled Nvidia GPU. Standard overclocking doesn't get me much because I get temp throttled. However undervolting, i.e., you boost clocks at lower voltages while not at higher voltages, leads to higher sustained clocks with _similar_ power/temps.

This is a consequence of power generally being linearly related to frequency and super linearly (even quadratically) to voltage.

Dumb question: why don't they do this from the factory?

Maybe stability margins, undervolting can also introduce instability.

Not a gamer but when I swapped my Ryzen 3700X out for an M1 Mac mini the temperature difference on my legs was the best feature.

I noticed a different going from an i9 MacBook Pro to an M1 Pro model. It’s faster, much cooler, I don’t have to listen to fans blasting all days, and I even have a visible dip on in my homes electricity usage.

I sympathise. A colleague of mine has an i9 MacBook Pro and it’s horrible and noisy.