4k 60hz will work with Intel Coffee Lake integrated graphics as long as you have one of the few motherboards with support for it. As out of all the Z370 motherboards available there are only three out there that can drive 4k60 over the onboard HDMI output and this is because they have HDMI 2.0 support. This can be super useful for building a custom PC without a graphics card whether it be a Small Form Factor build or simply not wanting to buy a shell out the money for a dGPU like with my latest build. I’m using a Gigabyte Z370N ITX motherboard with the iGPU only and I’m able to get 4k60 over HDMI with my 4k TV.
Since my 4k TV only has HDMI inputs I’m glad this motherboard has a onboard HDMI 2.0 otherwise I would have to use this external DisplayPort to HDMI adapter
HDMI 2.0 Z370 Motherboards:
The reason these motherboards are able to drive 4k60hz over HDMI 2.0 despite Intel Coffee Lake CPU’s spec sheets saying it only supporting 4k24hz HDMI 1.4 over the iGPU is because these motherboards have a DisplayPort to HDMI 2.0 LSPCon Converter Chip.
So despite there being no internal support on the Intel CPU chip there is support on the motherboard because of this DisplayPort to HDMI 2.0 converter chip soldered on to the motherboard. The really good news about this chip is the fact that it it also works on a my hackintosh, meaning that you can run 4k60 HDMI with integrated graphics if you have one of these motherboards and a HDMI 2.0 supported display. You can read more about using these motherboards on a hackintosh by reading 4k 60hz with HDMI 2.0 will work even on a Hackintosh using integrated graphics (iGPU)
Gigabyte Z370N ITX
ASRock Fatal1ty Z370 Gaming-ITX/ac
EVGA Z370 Classified K