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 Gigabyte GA-Z77X-UP7 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.
As have already said, that Gigabyte GA-Z77X-UP7 consumes more power than regular boards. The PLX PEX 8747 hub is only responsible for some of this power consumption, because this mainboard still consumes more power than other mainboards with the same hub, or even any other Intel Z77 Express based mainboard, which we have already reviewed. This is the price you have to pay for the super-powerful 32-phase processor voltage regulator circuitry and for the non-operational dynamic adjustment of the number of active phases depending on the operational load.
We see the exact same thing during overclocking. Only in case of maximum CPU utilization two mainboards had higher power consumption than Gigabyte GA-Z77X-UP7. ASRock Z77 Extreme9 shouldn’t be ashamed, because it overclocked our test processor to the maximum and therefore it worked at higher voltage, which naturally results into higher power consumption. However, it looks like Gigabyte GA-Z77X-UD5H-WB WIFI has an even less efficient voltage regulator. It has fewer processor phases, but it is designed as an Ultra Durable 4 product, i.e. uses less energy-efficient MOSFET.