Personally, I would stick with the white stuff on that CPU. I've busted two Durons now. Neither one was badly damaged, the chip off the second was so small that you had to use a magnifing glass to see it. Both failed immediately on boot and both were mounted with Arctic Slayer. I don't KNOW that AS contributed to their demise, but just to be safe, I'd stick with the white stuff.
The reason AS is supposed to be non-conductive is that it is a suspension of metal particles in non-conductive silicone oil. So if you stick two leads into a pile of it and try to measure conductance it will be quite low since there isn't a complete pathway for the electicty to travel from one electrode to the other. That works on the macro scale. What is unknown is how it works on a micro scale where an individual metal particle in the compound might be large enough to bridge two traces. We already heard several reports of people frying video cards witht he Arctic Slayer epoxy by letting drip down on the leads to the RAM chips. Better safe than sorry.