Separate from the important Radeon DPM support in Linux 3.11 that can sharply lower system power usage when using this forthcoming kernel update, there's been other power-related changes in recent Linux kernel releases.
I'm still in the process of expanded power consumption testing on modern Linux kernel releases, but it's a slow process with having a limited number of notebooks -- all of which are Intel CPU based, several of them being Apple systems, and most of the others being Lenovo ThinkPads. I've also done some testing of desktops with a USB-based WattsUp meter measuring the AC power draw in conjunction with the Phoronix Test Suite.
I'm in the process of writing up a multi-page article that shares more of my findings and results from a multitude of systems, which will likely come out in the next week or two. Yes, CONFIG_NO_HZ_FULL can play a role in power usage. Though for illustrating the mixed power results, today I uploaded results from an HP EliteBook that served as the Intel Software Development Vehicle (SDV) laptop for Sandy Bridge.
From the Core i5 notebook, the Linux 3.10/3.11 power consumption is actually a bit higher in some workloads than on Linux 3.8/3.9. Those new data points are available on OpenBenchmarking.org from 1308098-SO-INTELLINU35.