We perform our power consumption measurements with 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 on the PSU itself. In the idle mode we start the computer up and wait until it stops accessing the system drive. The mainboards are sorted in the order of ascending power consumption.
We know that MSI mainboards are generally economical, so the performance of the MSI Z87-GD65 GAMING isn’t surprising. Judging by our earlier tests of LGA1150 mainboards, the average level is about 45 watts, but the mainboards from ASUS and Gigabyte need considerably more power.
For all their downsides, Haswell-based CPUs should be given credit for requiring less power in idle mode in comparison with their LGA1155 counterparts. Unfortunately, we can’t see that when the mainboards work at their default settings, so we have an additional test mode called Eco. It means the same default settings but we manually switch all options referring to Intel’s power-saving technologies from Auto to Enabled in the mainboards’ BIOSes.
The results are better now and the ASUS-based configuration needs much less power. The results of the MSI mainboard are almost the same, though. According to our measurements, the power savings amounted to a mere 1 watt but we explained the reason in our previous review. The MSI Z87-GD65 GAMING just doesn’t allow you to enable each and every power-saving feature, which is why it is inferior to the ASUS Maximus VI Hero which uses them all. On the other hand, it is better than the Gigabyte GA-Z87X-OC which doesn’t benefit much from the power-saving modes.
We want to remind you that we install an AMD Radeon HD 7970 graphics card into our test configurations. If we instead used the CPU-integrated graphics core, the overall power draw would be lower than 30 watts. Haswell-based CPUs are indeed very economical when idle, so it is a shame that the mainboards do not ensure this advantage by default. You have to correct some BIOS options for that.
For power consumption tests under high load we run the LinX utility, which is a graphics shell for Intel’s Linpack test and supports AVX instructions. It is heavier on the CPU than ordinary applications, yet it is just an application nonetheless. It is quite possible that there are some other programs that can be just as heavy. That’s why we stick to using LinX for the purpose of checking the computer out for stability and for measuring its power consumption.
The ASUS Maximus VI Hero needs more power than its opponents because it doesn't use standard CPU settings by default. It increases the CPU clock rate, which explains the difference from the mainboards that ensure standard CPU settings.
The numbers are high overall, but they are close to the highest power consumption possible at all. To measure the power draw of our configurations in typical applications, we used the Fritz benchmark. It doesn’t really matter which exactly application you use for that purpose. Any ordinary program that can run on all four CPU cores will produce the same or comparable results. So it turns out that we shouldn’t worry about the high power draw under the AVX-using LinX. The typical power consumption is about 100 watts whereas the most economical mainboards need even less. The only difference is the ASUS Maximus VI Hero which consumes more power due to its nonstandard operating mode.
By the way, you have to count in the graphics card’s power draw at high loads to calculate the overall system consumption. We use high CPU loads in our power consumption tests, but if we load the AMD Radeon HD 7970 by running some heavy game, the total power draw will be close to 250 watts at default settings and even higher at overclocking.
Now let’s see how much power our configurations need when overclocked and working in idle mode. Since we try to enable all CPU-related power-saving technologies even when we overclock, the standings are the same as at the Eco settings without overclocking. The mainboards from ASUS and MSI don't need much more power here, and the ASUS is ahead of the MSI since the latter is unable to support certain power-saving states.
First of all, these Gigabyte mainboards need more power than average. Second, their power consumption gets higher in the overclocked mode whereas other LGA1150 mainboards have about the same power draw (perhaps a mere 1 watt higher) as at the Eco settings (without any overclocking). The GA-Z87X-UD4H and GA-Z87X-UD5H increased their power consumption by 4 watts, yet remained more economical than at their default settings. The GA-Z87X-OC also needs 4 watts more but benefits less from the power-saving technologies. As a result, it is the first LGA1150 mainboard we’ve tested which at low loads consumes more power in the overclocked mode than at the default settings. This seems to indicate certain problems with the power system Gigabyte implements in its mainstream and top-end mainboards.
When the overclocked configurations have some work to do, their power consumption is expectedly much higher than at the default settings due to the increased clock rates and voltages. The ASUS and MSI are comparable in that case whereas the Gigabyte GA-Z87X-OC remains the least economical among them.