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.
The mainboards are comparable in terms of their idle power consumption except that MSI is somewhat more economical and the ASUS Z87-Deluxe is less economical than average.
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. Unfortunately, the ASUS Z87-Deluxe is still less economical than the others, even though we turned on every option of the CPU Power Management subsection, some of which are supposed to lower the mainboard's idle power draw and have no counterparts in the other mainboards' BIOSes.
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 their BIOS options for that.
The high load on our Haswell is created by the LinX utility, a frontend for the Intel Linpack test, 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 under 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 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 but can even be lower with the most economical mainboards.
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.
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. 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.
We were not very pleased with the power consumption of the Intel DZ87KLT-75K in our previous review as it would need more power than expected. However, we thought that the DZ87KLT-75K, being a top-end mainboard itself, would look better in comparison with other top-end products. And indeed, the ASUS Z87-Deluxe is top-end and comparable to the Intel in functionality, but consumes more power at any loads and at any settings. Well, for all their indisputable advantages, ASUS mainboards have never been very economical.