@M1AF Interesting results. Few things that come to mind when seeing this:
What would the LLC3 refer to on Gigabyte motherboards? They use names like low, normal, medium, high, turbo, extreme.
I would consider it to be medium or high on a gigabyte board.
What was your reasoning for using the LLC values instead of defining a fixed voltage or voltage offset in the BIOS?
I have a pretty OP chip that I'm able to adjust LLC values only and get stable OC's. Stock LLC and voltage I can run 5.0. LLC3 and stock voltage I can run at 5.2. LLC3 and 1.45V and I can run 5.4/5.5 for cinebench runs etc. I let the system adjust the voltages because when I tested fixed or offset voltages I would get higher temps.
Would Conductnaut (liquid metal) help lower the temps even further?
A delid and liquid metal would likely reduce temps further.
Have you considered the Noctua L12S with a 120 slim under the heatsink blowing towards the motherboard and a regular 120 on the side panel above the L12S as intake? This would allow you to keep the PSU in the stock SFX positions with the fan exhausting towards the right panel.
No. I've found that the sinks cooling ability is directly in line with the size(weight) of the cooler. More sink area means more to soak. The L12S weighs less than a D9L, so I would expect it to perform worse than a D9L. Obviously throwing two 120's on it would help, but there are better options. I'd take a U9S over a L12S any day.
With a 9900k running @5Ghz, wouldn't you prefer to use an AIO to get lower temps?
Yes. AIO all day for a 9900K or any of the new high core count Ryzens. You'll get way better temps.
I like your solution for the GPU by removing the shroud and using the Noctua fans instead. I have a 2080S FE which has a rather small footprint and takes up only 2 slots. At the moment I have 2 120 slim fans set as intake. I'm debating replacing them with 2 regular 120 fans but fear it could cause turbulence.
The full size 120mm fans as intake into a FE card is a common configuration and I haven't heard any reports of turbulence, so you should be safe.
Have you considered 2 high static pressure fans (NF-F12) under the GPU instead to see if it improves your GPU temps?
I used to run two NF-F12's as intake on a 1080ti EVGA XC Black as intake, then as exhaust on the same card with an Accelero. I'll take the NF-A12x25's all day. They're way quieter and cool just as well.
Undervolting my 2080S has helped significantly. Without it the max temps were around 75c. With 0.906v @ 1920Mhz temps dropped to 67c max.
RIght now I run +49 core +1008 mem, 100% voltage and 125% power target. While gaming I'm at 1980mhz @ 1.069v 69C.