Wattman Power States voltage and MSI Afterburner Voltages per Power States?

[PontiacGTX]

I need to know if there is a way to check what are the voltage MSI Afterburner uses per power states, since MSI AB doesnt allow overclocking only wattman does, or Do I have to set the voltage manually , is there any guide what voltage difference there should be between power states"? any guide?