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 (including the proprietary ones) manually enabled. The difference between these two tests is usually quite obvious. Here is what it looks like for Asus Rampage IV Formula:
You can clearly see that if all power-saving technologies, including Asus’ proprietary ones, are manually enabled, the mainboard power-consumption is slightly lower in all modes. I have to remind you that this time we were unable to take advantage of the non-operational “CPU Power Phase Control” parameter, meaning that the special technology, which dynamically changes the number of active phases in the processor voltage regulator circuitry depending on the operational load, didn’t work. Had it been otherwise, the difference could be greater. However, when we tested the Intel DX79SI board, we didn’t detect any difference in power consumption at all. So, we should give Intel due credit for making sure that all power-saving technologies work on their mainboard absolutely correctly right from the start, so enabling them manually doesn’t have any effect on the system power consumption. This is definitely an advantage, but there is also another side to it. The new BIO finally has the options for configuring the proprietary power-saving tools, such as intelligent dynamic adjustment of the number of phases in the processor voltage regulator circuitry depending on its operational load. “Processor Power Efficiency Policy” parameter allows selecting different operational modes, but unfortunately, we didn’t detect any difference once we enabled the “Balanced” mode. Therefore, in this case, just like on Asus mainboard, there is no additional benefit from using the balanced or optimized mode.
As a result, if we compare the power consumption readings taken off tested mainboards in nominal mode, Intel board will always be more energy-efficient than Asus board, because it has all power-saving technologies up and running right from the start.
If we enable all existing power-saving features, the power consumption of Asus mainboard will reduce, but Intel board is still unattainably better.
And of course, during overclocking Asus’ power consumption levels are indisputably higher, because it overclocks CPUs better, among other things.
However, we have also measured the power consumption of both mainboards when the CPU was overclocked to 4.6 GHz on both of them. In this case, the obtained results will be a little different from what we have seen earlier.
In idle mode and under small operational loads Intel mainboard is still ahead, but under heavy loads its power consumption increases dramatically and Asus mainboard takes the lead.