There are millions of guides on here anyway, so I guess I'll list the main things to do and then, simply because I don't have your exact BIOS in front of me, you need to play around a bit and achieve the objectives. I think I am failry safe in saying the general consensous is as follows:
Find max FSB (That your MOBO can handle)
- stick the multi (CPU cmultiplier) as low as it will go within reason (6 or so is a decent number for a 2.4ghz 1066mhz FSB cpu)
- Make sure the RAM is on a ratio so that it is ALWAYS underclocked.
- Up the FSB by small increments (i'd do 40 max until it becomes a bit unstable, then use steps of 20, then 10) adding vcore if you need to (up to safe vcore for a 65nm Q6600 - which I'm sure can be found on this site in a sticky, probably in this very subforum) KEEP TESTING FOR STABILITY (occt is usually the most recommended program, again advice on how regularly and how long to run it for can be found on here easily)
Find Max CPU speed
- You now have a max FSB (beyond which MOBO/CPU is unstable) and a max Vcore.
- put it back to the stock multi (9) and up FSB, first to 333 (this should be very safe) and then maybe 360, 380, up to your max FSB OR to where it becomes unstable even with your max safe Vcore. repeatedly stress testing every time the CPU increases by a substantial (200 - 400mhz) amount.
- Now for some maths. Your CPU may be stable with a low multi and high FSB (if you've a very good MOBO) say 500 * 7.5 = 3.75ghz or it may get the highest clocks by using a high multi and lower than your "max safe FSB."
Find Max RAM speed
Simply play around with a very low multi and moderate to high FSB to get the max stable RAM speed. As with the CPU you can up the voltage and fiddle with various other things, like the timings to achieve stability.
Now for some more maths:
You know your:
Max CPU
Max FSB
Max RAM
FIND THE BEST COMBO THAT WORKS FOR YOU. THEN STRESS TEST ON OCCT FOR LITERALLY 8 OR SO HOURS. It is highly unlikely your max RAM and max CPU speed will happen at the same FSB, so fiddle aroudn to achieve a comprimise. If you game a lot then FSB & clockspeed yield higher FSB, faster RAM will yield much faster loading times for large applications.
EDIT: There are lots of small things that can be tweaked to achieve stability at higher clock speeds, such as north bridge voltage, ram timings etc that can all be read up in huge detail on this forum, most notably in stickies.
Also, I forgot (OCN may kill me for this) to say a really big WATCH YOUR TEMPERATURES!!!!!!!!!!!!!!
Temperatures are 95% of the time the limiting factor when OC'ing. most people draw the line at Temp < 60 during benchmarks that will only be run very very occasionally and max of 55 (celcius) during "normal" stressful activities such as modern games. Ideally you want temps as low as possible obviously...
