Overclocking Intel HD4000 iGPU. Additional voltage vs frequency.

I am just curious how much additinal voltage did you add and what is your max result. I can add frequency with 50Mhz steps to the clock and I also has the ability to add mV. If I set too high frequency without proper power will I boot on dedicated GPU I have? Most likely I will just power drain CMOS but still.
Lets skip the section where someone tells how bad Intel iGPUs are, why would I need it etc. Just post your experience. I am just curious and here we go.

 

Curious to hear how much performance gain you can get from overclocking an integrated GPU. Just curious

 

With 1250Mz it gives 841 points. NVIDIA GeForce GT 650M video card benchmark result - Intel Core i7-3720QM Processor,Micro-Star International Co., Ltd. MS-1756 score: P841 3DMarks

Here is what I found in the internet