VideoCardz.com posted Intel Kabylake CPUs will not work with Z370 motherboards, at least not yet
A quote from the article:
Looks like first Intel Coffeelake-S samples are already reaching reviewers. Intel Z370 says no to Kabylake Guys over at Hardware.info tested what we all wanted to know, the inter-compatibility between the sockets. The short story is that you cannot upgrade your KabylakeIntel Kabylake CPUs will not work with Z370 motherboards, at least not yet @ VideoCardz.com