Are you implying that the actual voltage is the one given by the dyn_nominal variable? From what I've read that's not the case, dyn_nominal is the voltage at which SmartReflex starts a new round of calibration and lowers from there if possible. The idea is that dyn_nominal is a stable voltage for that particular chip in all conditions, including after deterioration due to aging and at high temperature.

I can't actually set the voltage lower than the default calib voltage, so if I'm right undervolting is not possible, in fact, at least not with the current method.