I am seeing an amazing result if the stability test holds. I went in and set Vcore to fixed at 1.3 and moved LLC up to level 2. The system crashed going into Windows. I went in and set Vcore to 1.35 and kept all other settings the same (LLC=2, 50X CPU and cache multiplier, and -2 AVX). Not only did it boot into Windows, but I'm running Prime small FFTs now. According to CPU-Z, the voltage is 1.232 at 4.8 Ghz (small FFT uses AVX, meaning my offset comes into play). Not only that, but I'm seeing max temps have dropped 5-7 degrees across all cores! The MAX core temp after 15 minutes is 70 and most are still in the 60s. Frankly, I can't believe my eyes and am probably going to kill it and restart it to see if I really did pick small FFT. Core 0 has maxed out at 64 degrees so far!
EDIT: Bumped voltage to 1.375 after a crash and after 25 minutes, 4 of the 6 cores are under 70 degrees during the Prime small FFT with the other two maxing at 72 and 71. I'm really starting to wonder if the offset voltage on the Taichi Z370 is broken given the voltages I was seeing and 5-7 degree warmer temps.
EDIT 2: Coming up on one hour, and Prime is still plugging away while I type this message and surf around on the same machine. As it stands now, max temp on 3 cores is below 70 while the other 3 cores have reached 73, 71, and 70. Voltage is fluctuating between 1.248 and 1.264 during this Prime run. Very pleased if this holds up and I KNOW there are some more features I can disable in the BIOS - anyone have a link to a good recent overclocking guide for BIOS setting changes for Skylake or Kabylake? I think I have the voltages under control (or very close), I'm just wondering what other tweaks and changes I can make to lower temps and voltage while maintaining stability.