You are a liar because you crystallised your argument based on your search for an under-volt efficiency, not on whether the voltage setting can improve the efficiency of the rig depending on which frequency you are running, and that is where you went wrong. That you adamantly peddle that as fact in direct contradiction with even the datasheet, makes you an even bigger liar.

But we digress, OP's issue, like he stated, is about how they are powering the problem rig. If you want to split hairs as to which diodes you looked at and what the readings of your multimeter were when you were looking to undervolt, then I'll leave you to it.