Look at the results from anandtech. The Cortex A-15 consumes way more power than Intel's 5-year old Atom with a slight advantage in performance. Peak TDP for the A15 is a whopping 8W! Where is the power consumption advantage that we keep hearing about arm ???
At this rate where do you think the power consumption will be for armv8 with 64-bit? Intel products are BEATING arm in consumption now!!! Intel's power consumption LEAD will further EXTEND with Merrifield, Bay Trail and Broadwell.