I have a gigabyte P35 board in my sons rig, it will clock the E8400 up to 4.0GHz but nothign higher, the bios is limited for high FSB and not many options for volts...
Q9950 is not the best choice of chip for that board imo, a dualie would be better choice and much cheaper a decent E8400 chip will run 4.0GHz easy on that board