How important is CPU compatibility?

[Russinating]

How important is CPU compatibility within RAM specs? ie "CPU Compatibility: Intel Haswell-E & Intel Skylake". Will it not work with other chipsets such as Kaby Lake? Be fine? Or other issues?

 

[Russinating]

Thought so, never been a consideration before (been building PCs since pre-2000s), only motherboard compatibility, but currently experiencing issues and so trying to rule every possible out.