Last but not least the power consumption. We measure this using different methods. Note that in every case we show the power consumption of the entire test system, not only the CPU.
First of all we show the maximum power consumption during the Cinebench 15 benchmark. We also determine the average power consumption during the Adobe Premiere Pro benchmarks. Bear in mind that all CPUs are combined with a GTX 1080 Ti for the Cinebench benchmark; with the Premiere benchmark the processors with iGPU do not use a separate graphics card while other processors such as Ryzen and Skylake-X use an efficient GTX 1050 Ti.
The last graph shows the idle power consumption, in which all processors are combined with a GTX 1080 Ti in order to compare apples with apples.
The maximum power consumption in Cinebench 15 does show that the extra performance comes at a cost; the 8600K uses 36 percent more compared with its direct predecessor. With the i7s we see comparable numbers: the 8700K consumes 31 percent more power than the 7700K.
The average power consumption during the rendering of Hardware.Info TV is comparable with that of the 7700K. Once again the extra cores mean a higher power consumption and the 8700K uses about 20 percent more than its predecessor.
Next up: the efficiency, which we show in two ways. The first graph shows the amount of Cinebench points per watt. The second graph shows the total power consumption that is necessary in order to render the fragment of Hardware.Info TV in Premiere Pro. Bear in mind that all values are based on the power consumption of the complete test systems. This includes the motherboard, memory, storage, etc.
In these graphs it becomes clear that more of the efficient, fast 'Kaby Lake-cores' in the Coffee Lake processors leads to higher scores. With Cinebench the difference between the 8700K and 8600K is minimal, but with Premiere Pro the 8600K is clearly more efficient.