well 3.0ghz is stock speed just set the bios to auto whatever it puts it at should be fine. Intel recommends anywhere from .85 to 1.5 every chip is different so who knows what exactly it will need if i had to guess would be around 1.15 to 1.25 would be my guess.
It will depend on the VID of you particular chip. The VID is the voltage your chip programs the motherboard power regulator to deliver. It will be in the range of .85 volts to 1.5 volts. Lower VID's are better because they tend to give more OC headroom.

One way to find out is to go into the BIOS and take the CPU voltage off AUTO. Don't change it. Just take it off AUTO. The voltage that it is set to should be your VID.