You need to do the voltage mod to get more. It basically consist of soldering 2 variable resistors to your mobo and you can get a max around 2.5v.
you can read about it here.http://www.vr-zone.com/forum/Forum4/HTML/000440.html
The basics are a couple of 47k ohm trimmers connected between pin 7 and ground, and pin 10 and ground, of the IC that controls the processors voltage. I mounted mine on a small piece of breadboard stuck to the bottom of my case with Velcro. The whole project took under 20 minutes. To make the soldering easier, I would recommend using a third hand device to hold a pre-tinned lead to the IC leg.
Turn the trimmers to full resistance and boot the PC. Running VIA’s Hardware Monitor, slowly dial the pin 7 trimmer until you get maximum voltage. Mine peaked at 2.11 volts. Then slowly dial the pin 10 trimmer until the screen blanks and then back it off a bit. Your machine may reboot if you go to far. Pin 7 sends the voltage to the CPU, pin 10 sets the maximum voltage. Once the trimmer for pin10 has been set for maximum voltage you can then dial the pin 7 trimmer up for more voltage. I understand that 2.5 volts is about the maximum but have not read of anyone going past 2.3 volts for operation. Note that if you are air cooled you could overheat your CPU real fast. Be careful or your CPU could end up a crispy critter!
The 1st Phase of Voltage Mod with the vcore maxed out at 2.12v: