We benchmarked all of these systems with their related power-saving and performance-affecting features enabled: Cool’n’Quiet, SpeedStep, Turbo Mode, C1E. At idle, we let each configuration sit for 30 minutes before taking a measurement from the wall for the entire platform. Under load, we fired up Prime95 with the maximum number of threads per processor (eight for the i7s, four for the Core 2 and Phenom II) and FurMark to tax graphics.
At idle, AMD’s Phenom II X4 955, which scales all the way back to 800 MHz, uses the least amount of power. If you look back to our Phenom II X4 955 review, where we were forced to test with all of those extras turned off, the 955 actually used more idle power than Intel’s Core i7 920. Now AMD has a measurable advantage, besting all of the i7s and Intel’s Core 2 Extreme.
With load applied the 955 matches Intel’s Core i7-920. And, as you can see from another comparison to our last Phenom II review, using FurMark instead of the Vantage Perlin noise test taxes these platforms even harder. Not surprisingly, the Core i7-975 Extreme we’re testing today is the highest power consumer, though it doesn’t use much more juice than the Core 2 Extreme. The i7-950 falls right between the Core i7-920 and i7-965 Extreme, as expected.