VCCSA and VCCIO have been variously described to have safe maximums of either {1.20V, 1.20V} or {1.25, 1.20V}, and some OC'ing guide I'd encountered in the last couple days suggested that VCCIO could safely go as high as 1.25.
I can't speak for either Gigabyte board or the brand of your DDR4-3200 RAM.
On my Sabertooth Z170 S -- a mid-range of 12 phase-power-design and price -- and with G.SKILL TridentZ DDR4-3200 2x8GB 14-14-14-34 CR=2, I don't have to do anything with the VCCIO or VCCSA for error-free stability at 4.5, 4.6, or even 4.7 Ghz.
Some of the online guides suggest boosting VCCIO and then trimming it carefully if you're having trouble OC'ing RAM. Personally, since you can buy XMP memory at speeds I know of up to 3466 or thereabouts, there should be no need to try and squeeze more out of them.
Also, the indications I have are that you should never, never increase your RAM voltage above its XMP 1.35V spec, but I'm new to the Z170 chipset, and just getting familiar with the i7-6700K.
I MYSELF WOULD BE INTERESTED in the Ring or Cache voltage specs. I've seen a lot of folks don't want to mess with it. So the question is: how much can you improve the system by further tuning the cache speed and voltage? I thought I had seen where it didn't matter that much. If you know or think differently, I would like you to present your case for it so I can entertain a different view of things.
Like I said -- I'm new to 6700K and Z170 . . . .