> => Perf(CPUB) / Power(CPUB) = 1.6/1.3 * Perf(CPUA) / Power(CPUA) > => your CPUB is 1.6/1.3 ~= 1.23 (23%) better than CPUA
I guess here you make the same mistake Krashan did. Let's imagine a CPU A with performance of "1" and power consumption of "1". Now let's compare that to a CPU B with performance of "4" and power consumption of "2". It's obvious that CPU B with quadruple the performance but only twice the power consumption has a relative power saving of 50% compared to CPU A, because at the same performance CPU B would have only half the power consumption of CPU A. Now see the calculations for the relative power saving:
