# Why a lower voltage is better for modern fast CPU and other similar chips?

I started to use computers in the 1980's. As far as I remember 8bit CPUs of those times like Z80 were often powered by 5 V and used the same voltage for I/O signals. Later CPUs run at higher speeds and started to consume more power. I would expect that to deliver more power to a chip we must use either higher voltage or higher current. And since high currents normally need thick cables I would expect that CPUs would go for higher voltages to keep currents low. But the opposite is true. For example a standard Intel Pentium 4 or Core 2 Quad CPUs I use at home have 95 W TDP which means that they consume more than 100 W at power spikes. Since they run on a very low voltage around 1 V, they actually need to deliver the power using approximately 100 A. So here comes my question: Why is this preffered, why is it efficient?

• The CPU voltages are NOT chosen to optimise power supply factors - they are chosen to suit the characteristics of the ICs used. Modern CPUs use very small line dimensions and correspondingly small insulation layers. The voltages used are appropriate to the requirements of the transistors used in the ICs. May 7, 2014 at 18:34

$P \propto f_{CLOCK} \times C_{LOAD} \times V^2_{SUPPLY}$