After a tremendous amount of trial and error, we settled for the LLC-imposed 1.4 voltage for our tests.
We experimented with the Z490 Aorus Master's Load Line Calibration settings, but found that the auto setting provided the most stability. That obviously wouldn't be good for processor longevity, so we settled with dialing in an all-core 5.1 GHz overclock paired with a 1.3V vCore.
The 10900K did boot with an all-core 5.2 GHz overclock, though, but the requisite 1.4V vCore didn't prove stable unless we engaged aggressive load line calibration settings that pushed the chip over 1.5V during heavy workloads.
