You realize it is a electical component, and where you push higher frequencies the vcore will automatically rise so as to push the voltage high enough for the transistors to cross the threshold in transition from vcore to zero volt and back. the faster you increase the clock speed the shorter time the trasistors have to cross their threshold, if you lower the vcore you are not going to push the threshold and it won't fire. a 1.4+ vcore at 4.8ghz is pretty decent and obviously the board is of good quality to allow that. By pushing vcore up you create heat, by pushing it lower you will get instability neither are good.
Is there no AUTO vcore option, or manufacturer presets. Run if of the board manufacturers presets rather than screwing with vcore manually, the presets or auto will normally give you a 1ghz solid overclock without really pushing any component over the top.