The only CPUs you can tweek a Z170 or Z270 to run that are Coffee lake are the Pentium and i3s. Anything with 6 cores is off the table. You're basically running a Coffee Lake i3, as a Kaby Lake i5. That's how you pull it off.
Another project of mine. T3500 with a Xeon w3540, 12g of DDR3 ECC (triple channel), ATI HD4670, and other goodies. HD4670 is a place holder for another card so the finished build will be posted as well. Wanted to show off the mod to the factory passive CPU cooler, added a 80mm fan. Temps after 15min of compiling were 60c, down almost 10c.
Yes those are zip ties, yes it's a LED fan, no I have no shame.