overclocking 8700k Overclocking Puzzle: Fun for the Whole Family

[fruitofconfusion]

So here's a puzzle that I would love help with.

 

i just got an 8700k, and have it on an ROG Z370-G motherboard. Put on the preset 5 GHz Asus OC to get started, and that worked fine, and passed an Intel Extreme Tuning Utility (IETU) stress test.

 

i figured I could improve things, so I tried a few different OCs, including 5.1 at a lowish voltage (1.325 if I remember correctly), and that loaded but failed the test and crashed. I realized I could OC straight from IETU, so I decided to try that.

 

With little work, I was able to get 5.2 stable through a stress test at 1.33 volts (not a typo) on the CPU and Cache. Which seemed crazy to me, but I checked voltage and clocks through CPU-Z and HWInfo 64, and all looked good. I thought maybe it was a reported clock change with no actual difference, but the CPU benched 7% above stock.

 

Heres the kicker though. When I tried to load the voltages I used in IETU into the BIOS (just the 1.33, I couldn't see anything else through IETU), I couldn't even boot. It took me over 1.42 V through the BIOS to achieve the same clock as I got with 1.33 through IETU. 

 

My question to you: What in the world is going on?

[fruitofconfusion]

Chip ran better with XMP disabled, and AVX negative offset made no measurable difference.