Intel's decision to require a 300-series motherboard for the new Coffee Lake processors created quite a controversy. The chip giant says it set this requirement because older motherboards may not be able to provide enough juice, especially for those new six-core processors.
The only thing preventing someone from putting a Coffee Lake CPU in a Z170 or Z270 motherboard is a piece of software. VideoCardz reports a Chinese modder managed to get the Intel Core i3-8350K running on the high-end MSI Z170A Xpower Titanium motherboard.
This was achieved via changes to the BIOS and microcode updates, but it doesn't work 100%. While the CPU boots and works fine, the integrated graphics don't work and even the primary PCIe slot of the motherboard doesn't function:
The modder has successfully booted into Windows OS with i3-8350K processor installed on Z170 motherboard. BIOS modifications and microcode changes were necessary to make this work. However, saying that this mod works flawlessly is probably an overstatement. The integrated GPU is not available. In fact, even the primary PCI-Express slot is not working, but those might just be motherboard/driver specific issues. Further modifications could probably resolve such problems.