I'd run 400x8 once you get decent cooling. It's a cakewalk on most Q6600s.
SU - I'm confused by your post and request for help. According to your post you say that you want help getting to 3.0Ghz but then go on to say that when you set it at 3.0Ghz your temps are too high. 66C on that cpu is fine.
If you've already successfully achieved a 3.0Ghz stable overclock then what is your question? Temps? Temps are fine. If you want us to take a look at the settings you are using to get to 3.0Ghz please feel free to post up your current BIOS settings and we will be happy to take a look at them.
well it seems to be stable at times.. But some times on boot it boots up and then switches itself off and starts again.. and the TEMPS are 66C without load.. on load i fear its gonna reach 80.
Plus i want to know that what the settings should i do on the RAM and on the Proc as them dont seem to match and the sys gets slower .
Ex:- when i put the settings to 2.4Ghz ie. 400 X 6. then the Ram goes to 1600 which is the default settings of RAM, but the system gets even more slower.
What should the settings be of that their Cycles SYNC together ????