To be honest, and this is only my opinion. You are better not spending money on the chance you could overclock futher especially since you have a good overclock at the moment. Even if it does work and you get an extra few 100 mhz it wont make much of a difference. I doubt the 4th core would unlock on another board if it wont on this one you have now, if it would you would be able to get it going at a low clock on this board.
If you do have some spare money let what you have tide you over, start up a pile of money to go toward a full upgrade get your self a Sandy 2500k board and ram for £300 and let that last you a good 5+ years like the old q6600 seem to have lasted (and still go quite strong).
If you do have some spare money let what you have tide you over, start up a pile of money to go toward a full upgrade get your self a Sandy 2500k board and ram for £300 and let that last you a good 5+ years like the old q6600 seem to have lasted (and still go quite strong).