No problem.
BIOS overclocking is essential. Perhaps there is an option about vcore that is set to "Auto"? If you can change this to "Manual" you will be able to change the core voltage as you please. (Within the limits set by the mobo).
You should even be able to push it a bit WITHOUT changing vcore. Just up the FSB a couple of MHz, reboot the computer, and check for stability in Windows (Run folding@home, 3Dmark etc) and if it checks out OK, try upping the FSB a bit further. Loop until it is unstable. Then up the vcore a bit, and see if that helps..
Check out this article about your mobo
http://www.tomshardware.com/mainboar.../i850e-11.html
I like the nice blueish color!
Good luck!