Thats because it is relatively easy to increase the frequency if you have the power headroom to do so. You can see that the cores operate in a similar frequency range at the same voltage and process.I understand that, but my point was that Intel and AMD prefer to have a higher operating frequencies compared to Apple. Intel and AMD both seem to be targeting around 5ghz with their CPUs. If they didn't think frequency was important, why didn't they design a CPU with lower clock speeds and higher IPC over the years? Same for IBM.