We've measured the power consumption during two scenarios: idle (where we determined an average based on 5 minutes of idling) and under load, where we measured the maximum power consumption during Cinebench 15.
Do note: from this generation onward we use a different (and extremely efficient) power supply, which means that the measured power consumption will differ slightly from previous measurements. We also configure the motherboards differently: everything is tested at default settings of the BIOS now.
The lower positioned motherboards from MSI and Gigabyte seem to be more power efficient than the more extensive models from ASUS and ASRock, at least when idling. Especially the Gigabyte board is exceptionally power efficient: it's the most power efficient Kaby Lake we've tested up until now when idling. The differences under load are negligible.