So was it just one particular Asrock motherboard that allows this type of overclocking? Whilst my hardcore overclocking days are behind me, I have an i5-6500 and some kind of Asus mobo...I'm curious to take it for a test drive.
Many Z170 motherboards got this functionality, but keep in mind it's not without caveats.
It breaks integrated graphics, turbo boost, all power saving states, temperature sensing, and cripples the performance of AVX instructions for some reason.