You can overclock on the Z170X-Gaming G1 a few different ways. The first is using the EasyTune software. You can just click on OC to boost your system up to 4.4 GHz.
There is also an Auto Tuning feature. We gave that a whirl and it gave us a 12% or 4.5 GHz overclock.
If you want to venture into the BIOS there are also instant overclock settings there. If you find the CPU upgrade section it will give you instant overclocks from 4.2 – 4.6 GHz.
Finally of course you can fine-tune things manually in the BIOS yourself. Using the same process we did with Haswell we were able to bring our Core i7-6700K up from 4.0 GHz to 4.7 GHz. This was achieved by simply setting the multiplier to 47 and changing our CPU core voltage to 1.38V. This is a 100% stable overclock as it passed all of our benchmark tests as well as a stress and temperature test.