Welcome to the forums!
ok, first off, how in the HELL are you running that system with 550W?! Your DEFINETLY pushing it by OCing.
Second, im more of an AMD overclocker but as I beleive the qx9650 has an unlocked multiplier(?) and can be increased from the BIOS when you restart your computer.
If it isn't an unlocked multiplier, then just find the FSB clock in your BIOS and increase that in small increments, once you hit a wall with stress testing, SLIGHTLY increase your Vcore.
I'm sure an Intel OCer could help better than that but hope that shedded a bit of light