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).
If we compare the systems power consumption in nominal mode, ASRock Z77 Extreme4 becomes an indisputable leader. It is not only because this mainboard is simpler and smaller than the rivals. Another reason is that ASRock’s proprietary power-saving mode is enabled in the mainboard BIOS by default and in this case the processor Vcore is lowered by 0.1 V. Of course, ASRock Z77 Extreme6 mainboard also has this feature, and Asus P8Z77-V Deluxe even allows you to select the power-saving mode manually, but these power-saving technologies are disabled by default.
During system overclocking, when they appear in almost identical conditions, things do not really change that much. ASRock mainboards are obviously more energy-efficient than Asus in idle mode. As the workload increases the difference in power consumption between these mainboards grows smaller and practically disappears altogether under maximum load.