2 quick points #1-make sure you know how to reset cmos on your motherboard before trying to overclock anything because you will be doing it a lot! #2- make sure you have another computer available to use to get online just in case your computer won't start after your overclocking attemps.
F.Y.I. My QX9650 takes 1.37v to be Prime 95 stable (small fft) at 4.0ghz.
You have a QX9650, O/C will be a bit easier as u just have to adjust the multiplier instead of the FSB. Also like easymone9 said. Prime 95, OCCT, and other stress testing programs are availiable to check the stability of your O/C
dude, it's a "QX9650" it has an unlocked multiplier. Since you're obviously a n00b to overclocking, just keep increasing the mulitplier until you get a BSOD while running prime95. when you get the bsod, lower the multiplier back to the last good multiplier. this will keep you safe, and you'll probably get around 3.6 - 3.8 out of it. if you want to push it a little more, just add voltage to your proc. this will increase power consumption as well as produce more heat, and shorten the life of your proc (but you will get a higher overclock.)