We measured power consumption using Extech Power Analyzer 380803 device. This device was connected before the system PSU, i.e. it measured the power consumption of the entire system without the monitor, including the power losses that occur in the PSU itself. When we took the power readings in idle mode, the system was completely idle: there were even no requests sent to the hard drive at that time. We used LinX program to load the CPU. For more illustrative picture we created graphs showing the power consumption growth depending on the increase in CPU utilization as the number of active computational threads in LinX changed in nominal mode as well as during overclocking. The boards are sorted out in alphabetical order on the diagrams below.
Asus mainboards clearly stand out in the nominal mode, as they are the most energy-efficient of all. Note that Asus M4A89TD Pro consumes even a little more under triple-thread load, than it would consume under the maximum load of six threads. There is no mistake here, but yet another piece of evidence proving that AMD Turbo technology is extremely energy-inefficient. The CPU frequency increases, but its Vcore is pushed too high up in this case. As for all other tested mainboards, the power consumption difference between 3- and 6-thread modes is minimal. Just compare these results with what we got during CPU overclocking, when Turbo mode was disabled. The mainboards consume considerably less power under 3-thread load, than they would under maximum load.
Speaking of the power consumption in overclocked mode, we have to point out ASRock and Biostar mainboards. ASRock is not very energy-efficient in idle mode, but under maximum operational load it consumes less power than all others due to less aggressive CPU overclocking. Biostar mainboard is absolutely different: it is the most energy-efficient mainboard in idle mode, but consumes just as much power as all other testing participants even though the CPU was overclocked less. I have to admit that I was a little upset with a slightly higher power consumption of Gigabyte GA-890FXA-UD5 compared to other mainboards participating in this roundup.