Advanced Micro Devices Inc (AMD)

[chipguy]

Isn't AMD not far behind, even with a lower-frequency chip?

Bingo!

To execute an x86 instruction takes a certain amount of
logic gate wiggling. Regardless of whether a given level
of performance is obtained by wiggling many logic gates
relatively slowly or fewer gates faster, the amount of
power consumed won't vary greatly for a given process
feature size and supply voltage.