Question i9 9900K overclocking - confused, what to do with AVX, LLC and OCCT stress test fail

Sep 14, 2019

I've recently finished my rig with a custom watercooling loop. I got the ASUS ROG Maximus XI Formula board and the i9 9900K CPU.
Watercooling temps are a non-issue. Got a MO-RA3, so I can cool quite a lot of heat.

Started with overclocking following guides like i9-9900K at the Limit | OC the easy way | ROG MAXIMUS XI Overclocking Guide by der8auer and The Complete i9 9900K Overclocking Guide - Maximus XI Z390 and Others by Boosted Media.
I learned a lot of new things with those guides and googling a lot, even if it isn't my first OC.

My rig is mostly for gaming or photo editing.

Settings overview

I wanted to reach 5.1 GHz, and it seems like my chip may be able to do that. (5.2 GHz is impossible, crashes even in Cinebench at 1.45v)
I want to be as stable as possible though.

BCLK: 100
Core: 51
Cache: 48
Vcore: 1.36v (fixed)
DRAM voltage: 1.35v
VCCIO voltage: 1.15v
SA voltage: 1.10v
SVID: disabled
LLC: 7
AVX offset: 0

Here is an album of my exact BIOS settings, if this helps.

Vcore reads 1.305v during Intel Stress Test, 1.296v during Prime95 in CPU-Z.

Stresstest results

Cinebench r25 is the first test I do. Passes several runs without issues. (Avg 82°, Max 85°)
IntelBurnTest Maximum is fine as well. (Avg 68°C, Max 75°C)
Prime95 29.8 small FTT without AVX ran for 8 hours. High temps, but stable without errors. (Avg 84°C, Max 93°C)

I can't for the love of god run OCCT stress test. Neither the Linpack test nor the small data set test work. Both always crash right away. Medium works fine. (Avg 66°C, Max 69°C)
Can I just ignore those tests, because many sources seem to claim Prime95 should be enough, combined with the other stress tests I did?

Questions / Unclarity

Now I read a lot of differing opinions on stuff like LLC and AVX offset, and even more things. Which is really confusing. I know there a different ways to approach overclocking, and often different things all work, but I need something that works for me. Guess AVX offset could "fix" my OCCT test. Can run the small dataset with offset of 2. Getting a lot of temp errors though, because temps hitting 95°C regularly.

So is that high LLC really bad? With my voltage even the spikes of the vdroop shouldn't hit unsafe values, as far as I can guess. Tried lower LLC with 5, but I need to get a much higher Vcore in BIOS and it feels much less stable.
I can't run Prime95 with AVX. But I've read setting AVX offset higher is not that great because of fluctuating clock speeds in a lot of games then. Can I just ignore AVX then?

Haven't even started trying to squeeze a little bit more out of my RAM, and no GPU overclocking yet. Wanted to get the CPU stable first.

Any help how I can approach my OC and improve it is really appreciated.
Even if its telling my I should probably just forget it and go to 5.0 GHz with a lower voltage and much lower temps. Just thought with my cooler I could try it..