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. As in the performance tests, the results of the Gigabyte GA-Z87-HD3 with integrated graphics turned off are indicated as “GFX off”. The mainboards are sorted in the order of ascending power consumption. The results of the MSI Z87-G45 GAMING are colored differently for the sake of readability.
Default BIOS settings are not optimal whatever mainboard you take. That said, there are two models that stand out in terms of energy efficiency. Both are made by MSI and one of them is the Z87-G45 GAMING.
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 most of the configurations need much less power. The MSI Z87-G45 GAMING is still the most economical of all.
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 0.6.4 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 diagram suggests that none of ASUS LGA1150 mainboards can ensure standard system settings by default. ASUS's regular and TUF mainboards drop their CPU clock rate at high loads, lowering performance. And the ROG series increase their CPU clock rate, which affects their power consumption. That's not what we expect from the leading mainboard manufacturer. Compared to the mainboards with normal settings, the MSI Z87-G45 GAMING doesn’t look energy-efficient, though.
The numbers are high, 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 ROG series which consume more power due to their nonstandard operating mode.
Setting a higher CPU clock rate, the ROG series consume more power but deliver higher performance than other mainboards. Perhaps the performance boost is worth the energy loss? Well, the results of our tests don’t confirm that. The numbers vary depending on load, yet a 200MHz increase in CPU frequency results in a 5% speed boost on average. The power consumption grows by 13-14% at that. Thus, we don't think that this automatic overclocking implemented in ROG series mainboards is efficient. If you want to overclock, you will probably be able to increase the CPU frequency more and set its voltage lower, making your overclocked system more energy efficient than with the automatic overclocking.
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 the mainboards need in idle mode when overclocked.
We don’t have a special Eco mode here because we always use as many power-saving technologies as possible while overclocking. That’s why the standings are the same as in the Eco mode without overclocking. There are four economical models, the MSI Z87-G45 GAMING being among them. Four more are average in terms of power consumption, including the Gigabyte GA-Z87-HD3 with disabled integrated graphics. With regular settings, the Gigabyte mainboards need more power than others. The Gigabyte GA-Z87X-OC was in fact the first LGA1150 product we saw that consumed more power in the overclocked mode than at the default settings. The small Gigabyte GA-Z87M-HD3 is even less economical. Now the Gigabyte GA-Z87-HD3 sets a new record in terms of energy wasting.
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 mainboards are comparable in that case whereas the Gigabyte products remain the least economical among them.
As we know from our Gigabyte GA-Z87MX-D3H review, there is a bug related to power-saving technologies in Gigabyte’s BIOS. That’s why the company’s mainboards perform so poorly in our power consumption tests.
It is only at low loads that the overclocked MSI Z87-G45 GAMING is exceptionally economical. At higher loads it is just average in terms of power draw.