The vdroop mod increases the voltage fed to the chip, so it is natural for temp to go up. If you set, say, 1.4v in bios and your board has high vdroop the chip only gets 1.3v. If you mod the board, whether with a pencil or a hard wired mod, to reduce or eliminate vdroop, then setting 1.4v in bios will give the chip 1.4v.
In that example, the chip will be as hot at the 1.4v setting as it would be at the 1.5v setting before the mod. That's why you worry less about what you set in the bios and more what cpu-z says the voltage is under load.