We performed our power consumption measurements in nominal and overclocked modes using 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. The results on the diagrams are sorted out in ascending order.
Except for the traditionally economical MSI, the mainboards are comparable in the idle mode at their default settings. 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. This helps improve the results, lowering the power consumption of our configurations considerably. The mainboards from ASRock and Intel benefit less than the others from this, though.
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.
The high load on our Haswell is created by the LinX utility with support for 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 when measuring its power consumption.
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.
By the way, you have to count in the graphics card’s power draw to calculate the overall system consumption. We use CPU loads in our power consumption tests, but if we load the AMD Radeon HD 7970, the total power draw will be close to 250 watts at default settings and even higher at overclocking.
The mainboards are comparable in idle mode when overclocked, but the ASRock and Intel are again somewhat different, consuming over 40 watts.
We don’t have a special Eco mode here because we always use as many power-saving technologies as possible while overclocking. Instead, we show you a summary diagram with the power consumption of each mainboard at different settings. The results are paradoxical. The overclocked systems (working at increased CPU voltage) need as much power as in the Eco mode and less than at the default settings. It just proves once again how important it is to enable all power-saving technologies if you want your computer to be energy efficient.
The overclocked systems need much more power at high loads compared to themselves at the default settings. The high frequencies and increased voltages show up then.
As we mentioned above, mainboards from Intel and MSI used to be more economical than others. The MSI Z87-G43 proves it in our tests but the Intel DZ87KLT-75K doesn’t. Moreover, it needs even more power than its competitors in some operation modes. However, most of the tested mainboards are entry-level products. They are small and have but few additional controllers. The ASRock Z87 Extreme4 is the only one we’d call a mainstream model, yet the Intel DZ87KLT-75K is of a much higher class. That’s why the fact that Intel’s flagship mainboard is comparable to the others in power consumption is its advantage. When overclocked, it needs a little more power than its opponents in idle mode but less power at high loads. So, we guess we should wait for tests of other flagship mainboards to make our final verdict. It may turn out that the Intel DZ87KLT-75K will be much more economical than them.