EDIT: Here's where I got to, tl'dr I have a bad silicone lottery: https://www.overclock.net/forum/28277336-post29.html
I've recently upgraded from my long-standing Asus Sabertooth Z77 with a de-lidded Core i7-3770K (running at 4.5GHz) to an Asus Maximus Hero XI Wi-Fi with a Core i9-9900K.
As I learned 6+ years ago, it's always good to test the system on stock first; and I did that with the Core i9 system - Upon installing Windows I hit up the BIOS, tinkered with a few settings and put it on an old non-AVX built P95. Then, I ran the test for around 2hrs without any throttling or problems; temps were in the high 90s and I presumed the system was overshooting my voltage in order to guarantee a 5GHz OC (Asus MultiCore Enhancement set all 8 cores to 5GHz) - CPU-Z reported a VCore of 1.252V; HW reported a max of 1.332V-1.368V.
Below is a pic of my BIOS; essentially most things were on stock/auto; XMP1 + the Asus OC.
After testing my 'stock' system, I decided to start my OC'ing journey. I watched a multitude of guides, read a bunch of them - most had contradicting information, so I stuck with what I knew best - the same sort of settings that applied to my core i7-3770K (almost identical to a few guides I read of the i9-9900K).
Long story short, 5GHz ran into plenty of BSOD/auto-restart/P95 crashing but the PC staying in desktop; and right now I'm a bit stumped.
To put it into perspective, I ran manual VCore to 1.4V and it was still crashing (let alone the sky-high temps, which put me off 5GHz all together).
Even more of a mystery to me is my VCore readings in CPUZ and HW: If in the BIOS I set 1.32V, in the software programs without ANY load, I get around 1.28V; add 100% P95 load on it and with LLC Level 6-7 it drops to around 1.25V.
Okay, so what are the questions?
I want to know the following:
1. Why is my BIOS Vcore drastically different from my CPUZ/HW readings?
2. Why is my manual OC struggling, while the Asus auto OC seems to run fine in P95?
3. What can I realistically achieve with my Noctua D15 air cooler with this chip? I don't need 5GHz, but it would be a nice sweet spot
4. Why do I need 1.31V to run 4.8GHz?
5. Am I doing anything wrong with my settings/BIOS etc?
Just before answering, I've attached all my BIOS screenshots, below for my 4.8GHz 'OC'; it's currently running P95 as I type this - it failed at 1.3V after 2.5hrs.
FYI - I'm now running the latest P95 version and have disabled AVX2 and AVX1 in the custom field.
Any help would be greatly apprecaited