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).
Unfortunately, unlike performance, Gigabyte mainboards seem to have some issues with power consumption, and they mostly show in GA-Z77X-UD5H-WB WIFI. Some time back we used to explain high power consumption of the Gigabyte G1.Sniper 3 mainboard by the presence of the additional PCI-E bus hub on the PCB. Of course, it does contribute to the overall consumption, but today it became obvious that this chip wasn’t the only one responsible. While GA-Z77X-UD3H demonstrated more or less acceptable power consumption levels, Gigabyte G1.Sniper 3 and GA-Z77X-UD5H-WB WIFI consume much more power than all the other testing participants. Let’s recall the common features of the two: very similar or even identical twelve-phase processor voltage regulator circuitries. Large number of voltage regulator phases is necessary when the CPU utilization is very high, but if the CPU is idling or its utilization is pretty low, then the use of a multi-phase voltage regulator may backfire. To resolve this issue many contemporary mainboards use special technologies that allow dynamic adjustment of the number of active phases depending on the CPU utilization at a given moment of time. However, it looks like this function doesn’t work on Gigabyte mainboards.
I have to say that all processor power-saving technologies work correctly by default on both Gigabyte mainboards lowering the processor clock frequency multiplier and voltage in idle mode. If you change the parameters related to power saving from “Auto” to “Enabled” in the mainboard BIOS, the power consumption doesn’t change. However, previously Gigabyte mainboards had rows of LEDs indicating the number of active phases in the processor voltage regulator circuitry depending on the current operational load. Now the LEDs are gone, but the boards acquired 3D Power technology and there appeared a “3D Power Control” page in the BIOS with the “PWM Phase Control” parameter on it. We measured the boards’ power consumption with this parameter at its nominal “Auto” settings, as well as at “Extreme Performance”, “Balanced” and even “Light Power”. However, we didn’t detect any differences in results. So, our experiments confirm that the dynamic adjustment of the number of active phases in the processor voltage regulator circuitry doesn’t really work. This could be the reason why Gigabyte mainboards consume so much power, which becomes especially obvious on the models with multi-phase voltage regulators. Although, I am sure that it may not be the only reason.
If the power consumption is not too good even in nominal mode, then it is hard to imagine that things will change during overclocking. Therefore, it wasn’t surprising to see that Gigabyte mainboards again required more power than their competitors.