Power Consumption And Efficiency
Logging power consumption during the entire benchmark run gives us a window into the behavior of each processor and platform.
We’ll start by looking at the Core i7-3970X’s green line. A 150 W TDP should have been enough for us to know that high power consumption would be measurable. Indeed, the -3970X spikes up to use the most power under load.
What about the eight-core Xeon E5, which is also a 150 W processor? Despite that rating, its consumption is far below the new Core i7s, and in fact looks to be even more conservative than FX-8350’s power use.
Although the Core i7-3960X is only just slightly slower than the -3970X, the yellow line is quite a bit lower on our chart. And of course, the Core i7-3770K is downright miserly.
Averaging those power numbers out reveals that Intel’s Core i7-3970X fares worst. And although the Xeon E5 bears the same 150 W rating, it ends up using even less power than the 130 W Core i7-3960X.
Calculating efficiency requires that we know two things, though. First, we need the consumption figures above. Then, we need some measure of performance.
We capture this data by logging our scripted benchmark suite in two-second intervals. Multiplying out the number of resulting samples by two, dividing by 60 (minutes), and dividing by 60 again (hours) tells us how long each processor takes to wrap up testing.
Eight cores reign, it appears, though the Core i7-3970X and -3960X aren’t far behind. Opting for a Core i7-3770K gets you significantly lower average power use; however, it also takes 10 minutes longer than the -3970X to complete testing.
We’ll leave the FX-8350 alone in all of this. Its high power consumption and last-place performance are countered only by a $220 price tag.
Not surprisingly, Intel’s 77 W Core i7-3770K is the most efficient choice. More interesting is the fact that the 150 W Xeon combines brutal speed with lower-than-expected consumption to finish second in our efficiency metric.
Core i7-3970X isn’t able to add enough performance to make up for dramatically higher power use, and this reflects in its loss to the -3960X.
Then there’s the FX-8350, which, again, combines modest performance and high average power use, hurting its efficiency story.
