P45 was pretty good for overclocking and like the poster above me mentioned, raising clocks was done via the FSB primarily. Some engineering sample processors did have an unlocked multiplier but this wasn't much of an advantage as the later G0 stepping Q6600's clocked much better anyway.
My record for a suicide run was 4 ghz on a Q6600 on my DFI Lanparty DK P35 board so give that a shot at trying to surpass.
I had a GA-965p-s3 mobo and it was on the lower end of mid range boards. You won't see more than a small overclock with this board.