I think it's just the extra power options arm has. Scaling ARM speed just means writing to the PLL register of the CPU. Power usage is pretty much linear with f

I think it's just the extra power options arm has. Scaling ARM speed just means writing to the PLL register of the CPU. Power usage is pretty much linear with frequency and being able to go to 3Mhz one core from 2Ghz quad via the OS is excellent. x86 now has dynamic core and frequency speeds but it's not OS driven, the CPU does it on its own. Understandable since you can't just add such features to the ever compatible x86. So x86 can't be forced to scale down by the OS which is helpful on a phone (screen off = user won't notice apps running slow). Nothing inherent to the power/performance of the cpu itself. It's just that arm can and does get extra power saving features tacked on as required.