Overclocking on the Ryzen platform is not that hard at all. On the ROG Crosshair VI Hero there are a few ways to overclock. First ASUS has built in overclocking profiles already saved in the BIOS. All you have to do is go into the Extreme Tweaker tab and then into the Overclocking Presets menu. Here you can enable one of the preset profiles.
Unfortunately the 4.0 GHz profile was not stable on our system. So we decided to do our overclocking manually. So we put the overclocking tuner on manual, changed the BCLK frequency to 100 and the CPU Core Ratio to 39.
This turned out to be 100% stable with all cores rocking at 3.9 GHz. Temperatures were pretty normal too as you can see from the screenshot below.
It was quite odd to me that 3.9 GHz was so stable and 4.0 GHz seemed completely unstable. I would say this has a lot to do with how early we are into this platform and of course the chip we received as well. Other factors can be the motherboard you are using as well as the revision of BIOS. But as the platform matures I think we should see some great overclocks on this board.