Lower LLC reduces VRM temps, but can hinder stability if voltage is too low under load due to higher vdroop. It's good provided you aren't undercutting expected power delivery. I think it even improves transients. Offset seems to be preferred often over fixed, but there are case arguments I suppose in favor of each. I'm not 100% certain how it works with AMD and Ryzen in terms of offset and fixed voltages because it's rather clever with it's auto handling of things with PBO, but it still leaves room for manual overrides.
It's probably best to leave the voltage control to auto and simply reduce the LLC values downward to lower values and test out stability is under load and check performance temps to gauge the impact. You can experiment with the amount of LLC vdroop to find a balance sweet spot. Buildzoid even recommends lower LLC for z670 with Intel in his Aero D vs Aorus Master comparison video and what he mentioned fell in line with my personal experiences with LLC for Intel. I found the same situation LLC can in fact work better in practice. Something he mentioned about it was overshoot voltage and how lower LLC helps.
The LLC issue should really apply pretty equally in general to both Intel and AMD. A lower LLC will always be easier on the VRM design of the board though as a rule of thumb. The key is not dropping expected voltage so low that under load it causes a system crash.
I think vdroop use to be a worse issue on older higher node chips, but today lower node higher heat density chips the vdroop actually helps especially with chips scaling higher at lower voltages and heat density being higher thus thermals being a bigger concern while quick more dynamic scaling is easier and makes vdroop less concerning on stability sort of if it's still high enough for supplied voltage at load.
It's not going to hurt to reduce the LLC And see how it impacts temps and stability and is perfectly safe at the same time. It's worth trying when temps are already a problem.
Here's the Buildzoid video if interested.
Gigabyte z670 aorus master vs aero D comparison.
A lot of keen insight in his video analysis. What he alludes to is the same experience I shared for my earlier z170 board with LLC as well. The parts on the transients and oversight voltage are neat as well to the curious mind. It's funny where he mentions programs crashing too to voltages because there is a sweet spot on voltage being too low and causing a program crash yet not a outright system crash in certain cases.
I've so had that same experience countless times with overclocking. I'm sure most overclocking people remember encountering those in between sweet spots where a programs stable or up to a point and another isn't. That's essentially the struggle with LLC and voltage in general being lower than expected you can encounter a delicate balance of stability and instability when voltage is too far below expectations. You could have hard full system crash or just program crash. A full system crash usually means voltage is too low or temps too high which could be CPU, GPU, system memory, or board VRM's. A soft crash means it's not entirely unstable outright, but voltage are still too low or temps too high relative to what's required and/or expected for how far you're trying to push the hardware itself.
