When overclocked, with the CPU and GPU under peak load, the Intel Core i7-3770K platform outdoes the counterpart, Core i7-2700K, by the impressive 40%. With the integrated graphics core disabled, the difference is reduced to 36-37%. In the reference mode, the figures are different but the proportion remains the same.
The other pair shows a significant difference as well, but it's not as critical: 26% under peak load and 17% with a heavy load on the integrated graphics core.
Ivy Bridge remains less power-hungry, but without heavy load, the difference between the platforms is reduced: 23%-24% for the Core i7 pair and just +12% for the Core i5 one. The absolute difference is up to 12W at that. We conducted additional tests with lighter-load videos in WMP and MPC-HC, but the difference between playing back videos that put the heaviest and lightest load on the testbed was just 2-4 watts for each processor.
This diagram shows energy consumption of each platform for the period of 90 seconds. Unlike maximum power that may be a brief spike, energy consumption is more averaged out and objective. So, the difference between the Core i7 processors is 15%/18% (reference/overclocked), while that for the Core i5 CPUs is only 9%.
Note that while the energy consumption of the Sandy Bridge processors grows proroptionally to the maximum clock rate, that of the tested Ivy Bridge CPUs remains almost the same, with both GMA HD 2500 and GMA HD 4000. This lets us assume that Ivy Bridge solutions feature a higher-performance video decoder.
This is the only test mode, for which the diagram shows both minimum and maximum power results. The absolute figures (as well as relative, actually) are very similar in this case, the difference in three comparisons out of four not exceeding 8%. The only benchmark that produces somewhat different results is the comparison of maximum power for the overclocked CPUs. In this case, the Core i7-3770K saves as much as 18%. On the other hand, that's just 7W in absolute terms, no big deal.
Our measurements show that under heavy load, the maximum power of Ivy Bridge processors is up to 40% lower compared with Sandy Bridge. Reducing the load reduces the difference between the platforms down to the minimum of 8% in the idle mode. At that, the difference between the top-end Core i7 processors is the biggest. The difference between the Core i5 CPUs is down to nearly half of that. It also seems that Ivy Bridge can boast of the more power-efficient video playback, be it GMA HD 2500 or GMA HD 4000.
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