We leave the system to idle on the Windows 10 desktop for 5 minutes before taking a reading. For CPU load results we run AIDA64 CPU, FPU, Cache and Memory stress tests and take a reading after 5 minutes. The power consumption of our entire test system (at the wall) is shown in the chart.
Power consumption is in line with non-overclocked Z370 motherboards, perhaps a little lower because of the slower memory, though this is easily offset by variations in the way each motherboard vendor applies vCore voltage.
The default ASRock vCore was too aggressive given there is no overclocking supported and the CPU is running within Intel specification. The voltage was anywhere between 1.24 and 1.28 volts under load which is higher than it needs to be. It may well be worth using the UEFI settings to reduce the core voltage down to 1.175-1.2 to save power and lower temperatures.