Thanks to justapost's help, my situation has become clear:

MaxVID is controlled by a read-only register: MSRC001_0071

The processor itself references any change to the current VID register against that one and the following takes place before signaling a change to the voltage controller:

If MaxVID < NewVID Then CurrentVID = MaxVID
ElseIf MinVID > NewVID Then CurrentVID = MinVID
Else CurrentVID = NewVID

Only processors with a MaxVID/MinVID of 00h are allowed to set to anything [except for 0V].

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Anyone want to help me figure out a hardware mod? Perhaps it could be as simple as a pencil trick?