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Power Consumption

One of the most intriguing features of the LGA1156 processors is their thermal design power of 95 W. It is 35 W lower than the thermal design power of almost the same LGA1366 processors. If we add here the considerably lower heat dissipation of the chipset on LGA1156 platform, then we can expect the new Intel platform to become a pretty attractive solution in terms of performance and power consumption ratio. And most likely this platform will even be able to compete against LGA775, which we have long admired when it comes to energy-efficiency.

However, it is very reckless to take the manufacturer’s promises for granted in this case. Therefore, we tested the actual power consumption of all participating platforms. The following numbers show the total power consumption of the tested platforms (without the monitor). During our tests we used 64-bit LinX 0.6.3 utility to load the systems to the utmost extent. Moreover, to ensure that we estimate the power consumption in idle mode correctly we activated all power-saving technologies, such as C1E, Cool'n'Quiet 3.0 and Enhanced Intel SpeedStep.

In idle mode the power consumption of the LGA1156 platform looks better than impressive. Among all today’s testing participants it is the Lynnfield platforms that consume less power of all. It happened due to the fact that processor power-saving technologies have once again been improved in the new CPUs. In particular, Core i7-870 and Core i5-750 processors can drop their frequency to 1.2 GHz and their core voltage to 0.85 V.

The situation looks pretty good when we measure the power consumption under load. LGA1156 systems are definitely more economical than LGA1366 platforms, their power consumption became more than 50 W lower. Moreover, the Core i5-750 system that doesn’t support Hyper-Threading turns out even more energy-efficient than LGA775 platforms. In other words, our expectations came totally true: LGA1156 systems cam offer better performance-per-watt than any other solutions. More to that, Intel also plans to release special energy-efficient LGA1156 processors, so this platform has every chance to become the ultimate favorite for those who care about their electrical bills.

To get a better picture of the situation we also tested the power consumption of the processors and mainboards under heavy load without taking into account the rest of the system components. To be more exact, we measured the power consumption along the 12 V power line connected directly to the processor voltage regulator on the mainboard and along the mainboard power lines.

Strange as it might seem, but the lowest power consumption among all the testing participants belonged to Core i5-750 processor, which turned out more energy-efficient than even Core 2 Quad Q9400. However, low power consumption demonstrated by CPUs on Nehalem microarchitecture can partially be explained by their voltage regulator design. The thing is that the isolated 12 V power line is only used for processor cores. As for the Uncore part of the CPU, it is powered from the mainboard via a 24-pin connector. That is why this time we also decided to include the power consumption readings taken off the mainboard.

Keeping in mind everything that has been just said, it is no wonder that LGA1366 and LGA1156 mainboards are most energy-hungry. Uncore part of the CPU contributes significantly into the results of our power consumption measurements. Nevertheless, we can’t help noticing that elimination of the North Bridge in LGA1156 systems did in fact make the corresponding mainboards more energy-efficient. The power consumption difference between Bloomfield and Lynnfield mainboards reaches 20 W overall.

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