Using the GeForce GTX 980 Ti graphics card we see no real performance gains from the new Kaby Lake processors when testing with Ashes of the Singularity.
The 7700K was just 2% faster than the 6700K in Overwatch and that gain can of course be put down to the higher operating frequency.
The last game we looked at was Grand Theft Auto V and again small gains were delivered by the Kaby Lake processors. We could have shown the results for another dozen games and the margins would have looked much the same.