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). The results of Asus P8Z77-V Premium are marked with darker color for your convenience.
Because of compatibility issues we uncovered in Gigabyte GA-Z77X-UP4 TH and Gigabyte GA-Z77X-UP5 TH mainboards with our original CoolerMaster RealPower M850 power supply unit, we had to replace it with Enermax NAXN ENM850EW. Both these PSUs have very similar technical characteristics, but Enermax NAXN ENM850EWT is about 1-3 W more energy-efficient than the Cooler Master unit. In order to be able to use the previously obtained results, we decided to make up for this efficiency difference by adding 2 W to all new power readings, so that we could still compare their results against the power consumption of all previously tested products.
We knew beforehand that the additional PLX PEX 8747 hub makes Asus P8Z77-V Premium mainboard consume more than an average board. We tested three mainboards with this controller and all of them demonstrated significantly different levels of power consumption than the other testing participants. However, you can slightly improve the board’s energy-efficiency if you manually enable all power-saving technologies in the BIOS.
During system overclocking when there is insignificant load or none at all, Asus P8Z77-V Premium consumes more power than average, which is typical for mainboards with the PLX PEX 8747 controller. However, under maximum operational load the board suddenly became pretty energy-efficient, compared against Gigabyte G1.Sniper 3 mainboard, which overclocked the processor to the same 4.5 GHz. Yes, ASRock Z77 Extreme9 consumes much more power in this case, but it also overclocked the test CPU better.