Just from what I have read here, getting 3.0Ghz is not a problem with the Q6600, even the B3 stepping can do it. Getting 3.6Ghz usually requires a substantial increase in vcore, most reporting above 1.4v and this is with a vid of 1.27v or lower. I would imagine with a higher vid you would need at least 1.45v or higher. My vid is 1.265v and I need 1.47v to be OCCT stable. Although the vid isn't the only thing to determine how high you can overclock it is usually a good indicator.

Utnorris