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Power Consumption

We performed our power consumption measurements using an Extech Power Analyzer 380803. This device is connected before the PSU and measures the power draw of the entire system (without the monitor), including the power loss that occurs in the PSU itself. In the idle mode we start the system up and wait until it stops accessing the hard disk. Then we use LinX to load the CPU. For a more illustrative picture there are graphs that show how the computer power consumption grows up depending on the number of active execution threads in LinX (both at the default and overclocked system settings). The mainboards on the diagrams are sorted out in alphabetical order.

We often point out that on many mainboards certain power-saving technologies are disabled by default. Therefore, besides power consumption in nominal mode with all default settings, we also measured the power consumption of test systems with all power-saving technologies manually enabled. The difference is usually very noticeable. Here is what it looks like for Asus P9X79 Deluxe, for example:

You can clearly see that if we enable all processor power-saving technologies as well as Asus’ proprietary power-saving tools, the power consumption will drop significantly in all modes. However, we didn’t detect any difference on Gigabyte GA-X79-UD7 and Intel DX79SI mainboards. Therefore, we should definitely give due credit to Gigabyte and Intel for implementing all Intel processor power-saving technologies correctly, so that their manual enabling doesn’t have any effect on the system power consumption. This is a definite advantage of both mainboards, but there are also a few shortcomings. The BIOS of both Intel and Gigabyte boards has finally acquired an option that allows configuring proprietary power-saving technologies, in particular, Intel mainboard now offers intelligent dynamic adjustment of the number of active phases in the processor voltage regulator circuitry depending on the CPU utilization at a given moment. “Processor Power Efficiency Policy” parameter allows selecting one of the three possible modes, but unfortunately, we didn’t detect any difference between the “High Performance” and “Balanced” modes. Therefore, the “Balanced” mode doesn’t deliver any additional benefits in terms of power-saving, just like on Gigabyte’s mainboard.

As a result, if we compare the power consumption of the tested mainboards in the nominal mode, then Gigabyte’s mainboard will outperform Asus under any type of load, because it has all power-saving technologies up and running by default, unlike the Asus board.

The situation changes if we enable all power-saving technologies manually. Gigabyte mainboard remains the winner under low loads, while Asus mainboard takes over the leader under heavy loads, because besides Intel power-saving technologies, its own proprietary ones also kick in.

However, while Asus and Gigabyte are preoccupied with competition against each other, we get the impression that they are manufactured using a different production process than the Intel board, because its advantage over them is simply unprecedented. Of course, it is still there in overclocked mode, too, especially since Intel board doesn’t overclock too much.

I have to say that the energy-efficiency of the Intel DX79SI mainboard totally makes up for the low performance and low overclockability. The maximum performance difference between the boards is around 10%, but even the minimal difference in power consumption between them is way higher than that, and the maximum difference is as high as 30%!


When we started reviewing Intel DX79SI mainboard, we didn’t expect such an outcome. It looks fine, has pretty good set of features, which is not very much different from what we saw by other mainboards of the same class. It has a few advantages and a few drawbacks, just like everyone else. However, when tested in identical conditions the board demonstrated surprisingly low performance in nominal mode and even lower performance in overclocked mode, because it proved unable to fully overclock the CPU and memory at the same time. However, the board’s phenomenal energy-efficiency fully makes up for the not very high performance, although this is not quite what we would expect from a flagship product. When we are looking for energy-efficiency in the first place, we go with a platform that uses different type of processors, and an LGA 2011 platform is supposed to deliver maximum performance, which Intel DX79SI can’t do. I also have to say that BIOS updates from Intel often change not only the BIOS functionality but also its appearance. So, there is some hope that things will change. However, as of now we could only recommend Intel DX79SI to those users who care for energy-efficiency of their system more than speed.

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