You gain a some capability for overclocking with a Z board and an non-K CPU. The non-K CPU has a locked multiplier. Some of the early Z170 boards let you manipulate the BCLK strap and change it from 100Mhz to other values like 125Mhz. Then you could effectively overclock a locked CPU.
However, Intel put a quick stop to this since it made their product differentiation somewhat pointless. All motherboards after a certain date no longer supported this feature with locked processors. That information is still out there, but I don't think you'll find any of those boards, it was years ago.
Best you can do is force the multiplier to stay in boost all the time and push the BCLK from 100Mhz to 103-105Mhz at most. Might get an extra 100Mhz out...