The 7 series are more efficient than the 5 series. They just are programmed to go as fast as thermals allow. So the reviewers that had really powerful coolers on the cpus saw really high power draw. If instead you set a power cap, you get higher performance per watt than the previous generations.

Having the clocks scale to a thermal limit is a nice feature to have, but I don’t think it should have been the default mode.