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.
The OP raised voltage setting, all adseb and I pointed out was that is does not actually change the core voltage. If the S3 was not well past it's sell by date I would persist in the discussion, however as it's now academic I will call it a Day on the S3 Voltage setting discussion.
If anyone else want's to chip in with their experiences of software voltage setting on an S3 then please do so. I for one have had my fill of being called a liar in every other paragraph...
Rich