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Power Consumption

The previous enthusiast platform, LGA 1366, wasn’t particularly energy-efficient. Although Gulftown processors were manufactured with contemporary 32 nm process, their calculated TDP was set at 130 W. Moreover, the two-chip Intel X58 Express chipset with 29 W TDP also contributed substantially to the overall power consumption. Do we expect the new enthusiast platform to boast dramatically reduced power consumption levels? No, the new six-core processors also have 130 W TDP, just like their predecessors, which results from their hidden eight-core origin. So, the only improvements we could count on will come solely from the chipset, which has been cut down to only one South Bridge chip with 6-7 W TDP.

Unless states otherwise, the graphs below show full power draw of the computer (without the monitor) measured after the power supply. It is the total of the power consumption of all the system components. The PSU's efficiency is not taken into account. The CPUs are loaded by running the 64-bit LinX 0.6.4 utility. We enabled all the power-saving technologies for correct measurement of the computer's power draw in idle mode: C1E, C6, AMD Cool'n'Quiet and Enhanced Intel SpeedStep.

In idle mode the power consumption of the LGA 2011 platform has significantly improved compared with the power consumption of the LGA 1366. However, it still can’t catch up in this aspect with LGA 1155 systems, although Intel has made significant effort, namely, implemented a much more aggressively working Enhanced Intel SpeedStep technology. Core i7 processors from the new 3000-series can drop their clock frequency to 1.2 GHz, while the lowest multiplier for the regular Sandy Bridge processors was 16x.

When the CPU is loaded with only one thread, LGA 2011 platform consumes even more power than LGA 1366. This is the back side to Turbo Boost technology that very aggressively overclocks the new Core i7 processors from the 30l00-series. Besides, do not forget that the semiconductor die of the LGA 2011 processors is twice as large and twice as complex as the Gulftown die manufactured using the same 32 nm process.

When all processor cores are fully utilized, the LGA 2011 proves even more power-hungry. Even Core i7-3930K, not to mention the Extreme Sandy Bridge-E modification, consumes more than Core i7-990X. In other words, the migration of high-performance enthusiast processors to the new Sandy Bridge microarchitecture didn’t have any positive effect on energy-efficiency aspect. Moreover, if you decide to go with LGA 2011, you may completely forget about energy-efficiency to some extent: this platform is designed for breaking performance records and not for saving power.

For your reference we would like to show the power consumption under full load, which was measured in processor and mainboard power lines separately:

If we compare the power consumption of the LGA 2011 and LGA 1366 platforms, we will notice one more interesting thing. The simplification of the chipset design in the new platform did have a positive effect, which shows in the lower mainboard power consumption. But the LGA 2011 processors consume obviously more than their LGA 1366 predecessors, although they have a very similar thermal envelope. If we compare the power consumption of the LGA 2011 and LGA 1155 platforms, we will see that newcomers require about twice as much power. This is an excellent illustration of the differences resulting from the fact that Sandy Bridge-E processors have twice as many computational cores as the regular Sandy Bridge.

 
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