There is a lot of difference between "preapplied" and doesn't require. You've got it already so that means obviously you didn't need to add any, that doesn't mean it doesn't require it.
I've ran a couple athlon cpu's short term w/o any at all, w/o issues. The temps where a little high but nothing that would cause problems. However I would recommend it simply adding some AS3 cut temps in those case by a fairly good amount.