why does CPUs/CPU cores seem to be capped at 3 – 4 Ghz since almost a decade?

Question

why does CPUs/CPU cores seem to be capped at 3 – 4 Ghz since almost a decade?

In: 1368

Answer 1

Heat

Transistors dump a tiny bit of energy each time they switch, and the amount of energy is based around the transistor(gate capacitance) and the square of the voltage you’re running it at. If you want a given transistor to switch faster you need to increase the voltage.

A 10% increase in clockspeed might require a 5% increase in voltage which results in a 21% increase in heat generation, and the scaling gets worse the faster you try to go.

You can also make the transistor switch faster by making it smaller but that also lets you pack more in so your heat generation per area remains about the same

We’ve instead switched to lots of medium sized cores running at moderate speeds which keeps temperatures down while still providing good performance on heavy workloads. Things that aren’t designed to run on multiple cores do suffer a bit, but there isn’t a ton you can do to improve that these days.