Yes I hear all these answers and opinions. If you stretching out that much on a 7700K, those funds can go on a brand new z370 mid range board and slap in a 6core 8400.
Its simple, if you dont want to bottleneck your card and save Green, get a 7600 (non K). If your gonna be spending some Green for a K version, all that cash would be better suited for a z370 with a better upgrade path rather than spending it on a 7700K on a low end motherboard.
I personally would not be spending money on a 7700K unless you can find one dirt cheap. Sure performance is great, but you have no upgrade path on a low end motherboard. Forget OC as the VRM on that board would be a joke
To answer your question, the K versions on Coffee Lake CPU's are clocked higher out of the box, without an OC