Or you can set the vcore manually. I ran a series of stress tests progressively lowering the vcore until it failed then bumped it up one notch to remain stable.
I did the same and found my i5 6600k stable at 4.6GHz at 1.290V vcore, however, when I enabled XMP to get my RAM to run at 3000Mhz the temps jumped 10 degrees. When I selected "Relax OC" under Enhanced Memory Settings my temp went back down.
I still have not figured out how to implement an offset vcore on the gigabyte mobo. I have set vcore to NORMAL which allows me to adjust DVID but and negative offset fails. Even a slight -0.005 offset which makes no sense.