look in the manual, it should mention some things about changing your Core Voltage and Front Side Bus settings. Your bios should have an option to let the user define the cpu. You can go from there!!
PS, here is how your speed is calculated
Multiplier(Fixed with an Intel) * Front Side Bus = CPU Speed
Example 10.5 * 66 = 693(round to 700) This is what you have Now overclocking we can
10.5 * 75 = 788
10.5 * 83 = 871.5
10.5 *100 = 1050
You will probably have to up your voltage to get to the gigahertz mark, don't go too far, stay under 1.9 volts if possible. Also, make sure you have a good cooler, you can get a stable system at 871(see my sig) with the retail, but you will not get higher. When I get my new heatsink, I am going for a gig. So good luck to you, and hope this helps!