Something I've been thinking about and haven't seen anyone address really.
Recently some material has been leaked from the AMD's ISSCC presentation:
https://videocardz.com/65774/more-details-about-amd-zen-cpu-core-revealed-at-isscc
The curious tidbit is this:
The material claims that AMD has a local LDO voltage regulator. LDOs are typically linear but in other article I've seen a mention of the term "digital LDO", it's kind of a weird name but anyways I think this is a switching regulator.. as linear regulators would make no sense (they waste too much power).
Why am I bringing this up? Well anyone who's worked with electronics can tell you that voltage regulators/LDOs or whatnot have a dropout voltage. I think one of the reasons we've been seeing higher than usual voltages in various screenshots (1.87v in that 5.2Ghz LN2 OC and 1.35v in that Ryzen Master screenshot for 3900Mhz) is because of the dropout voltage needed to compensate for this LDO.
The voltage being reported is the voltage at the Vin or at the VRM.. but the cores need a certain margin to compensate for the dropout in each LDO regulator.
So this is something to keep in mind when thinking of voltages.