It became known as Intel made processors Coffee Lake is incompatible with motherboards for CPU previous generations
Intel is known to frequent changes in processor sockets, making new CPUs are incompatible with motherboards for their predecessors and increase the cost of upgrading a PC. In the case of processors under the conditional name Coffee Lake connector remains the same, but they are still incompatible with motherboards for processors Kaby Lake and Skylake in the same execution.
Using the information from the Intel website, the source is clearly shown, in what the reason of incompatibility. The fact that the manufacturer has changed the purpose of some of the findings.
More specifically, in Coffee Lake more contacts is used to supply voltage VCC. In the illustrations they are shown in red. At Coffee Lake (upper illustration) of their 146 pieces, and Kaby Lake and Skylake (the lower illustration) — 128.
Thus, the inherent incompatibility at the hardware level and, contrary to previously unheard hopes, can’t be fixed with BIOS update or other software tools.