crazipper writes "Back when Intel launched its Core i5/i7 'Lynnfield' CPUs, Tom's Hardware ran some tests in Windows 7 versus Vista to gauge the benefits of the core parking and ideal core optimizations, said to cut power consumption in the new OS. It turned out that Win7 shifted the Nehalem-based CPUs in and out of Turbo Boost mode faster, resulting in higher power draw under load, while idle power was a slight bit lower. The mobile version of the architecture was claimed (at the time) to show a greater improvement in moving to Win7. Today there's a follow-up with the flagship Clarksfield processor that shows the same aggressive P-state promotion policies giving Win7 a significant performance advantage with Core i7 Mobile. However, power consumption is higher as well."