Like stated above its a different between vcore supplied to processor when its idle and under load.
Ideally vdroop is there for a reason. To protect the processor from peak overshoot. Its not an issue unless you are into extreme ocing. And by that I mean pushing absolute limits of your hardware. Most enthusiasts wont even need this for this board.
Some people dont do this mod as they dont have skills to do this mod are are afraid to do it themself, so i am giving you an option.