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. 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.
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 ECS Z77H2-A2X (v1.0) are marked with darker color for your convenience.
We have already mentioned that all power-saving technologies are enabled and working properly on ECS Z77H2-A2X (v1.0) right from the beginning, therefore, its power consumption in idle mode is very low. However, once the CPU starts working hard everything changes. Even under low single-threaded load the system power consumption increases above average, while maximum CPU utilization places the board among those models that have an additional PLX PEX 8747 hub onboard. This hub increases the overall mainboards power consumption, but offers extended functionality in terms of supported graphics configurations in return. However, ECS Z77H2-A2X (v1.0) doesn’t have any additional hubs, yet its power consumption is unjustifiably high.
In overclocked mode the board’s power consumption in idle mode and under minimal operational loads is average, but once the CPU utilization rises to the maximum the power consumption goes beyond average level. It is important to remember that the board managed to overclock the processor only to 4.5 GHz, and had it hit the 4.6 GHz maximum, its power consumption would have easily become the highest of all tested mainboards. During our preliminary overclocking tests it grew as high as 200 W, which is something we have never seen before on any of the tested boards.