While there is no official confirmation from Intel that Z370 chipset motherboards will only support Coffee Lake CPUs and won't be backward compatible with Kaby Lake CPUs, some reviewers have already tried to run some Kaby Lake CPUs in a new Z370 motherboard.

Hardware.info site tried to boot up a Kaby Lake-based Celeron G3930, which fits perfectly into the "new" LGA 1151 socket but the motherboard simply did not boot and got stuck at VGA detection stage.

Since the new Coffee Lake CPUs can only be used on the Z370 chipset motherboards and won't be compatible with Z270 motherboards, this move from Intel does not come as a big surprise.

Intel could theoretically give a green light to motherboard manufacturers to enable backward compatibility with a BIOS update in future but we simply don't see that happening.