Even though these CPu are hot, the 965 is MUCH better than the 955 heat wise. It's on 65nm and should no be this hot IMO.
What I think the problem is that the heatsink doesnt sit properly on the CPU. Now since both heat sink did'nt seam to do the job im a bit clueless as to why it would make a proper contact. I would take of the heat sink and the CPU and reseat the cpu. If it has even a slight angle and the heat sink make contact with only half the heatspreader, it wont help.
Artic silver wont be magic, only thing is that it might apply better than the one you had. You have to put a really thin layer. Zalman released a new product that is suppose to be amazing,
Zalman look for the ZM-STG1 in optional product, why I'm posting it is because it's much easier to apply with this sort of nail polish finish. Finally im not positive it would be a good idea but you could polish your heatspreader and Heatsink so they make a perfect contact(polishing/removing the heat spreader will probly void your warranty so not the best solution).
Last point, what's you case? how's gthe air flow? you can ahve the best heatsink in the world, if hot air does'nt have anywhere to go than your CPU will get warm. make sure you have proper cable management and enough fan in your case.