There are often times, a board manufacturer will not even apply thermal paste to their chipset heatsink! Before you try for high FSB speeds you will want to remove your chipset cooler and at least lap it so that it's nice and smooth to get as many of those cracks out as possible. This one in the picture was not only lapped but polished. The polishing was just to show you a nice mirror finish so that you can see how smooth it is.