i used p35 and ddr2 to oc my q9550, i think g31 is a bit weak for oc. if you have ddr3 ram, you would need a p45 board. if you can find a x38 or x48 board, those will be the best.
i suppose you would like 1600 fsb to push the 2.83ghz to 3.4ghz, keep in mind that memory plays a huge role in oc. i'm having issue pushing my chip higher than 3.4 due to slow ddr2 800 ram.