pagos,
That's great to hear, but it is highly doubtful that just the change from stock thermal paste to the PK-3 dropped your temperatures +23C. Perhaps it was the way that your cooler was sitting or a slight error during installing the fan the first time.
I am currently using Arctic 5, but I have also ran these same tests with IC Diamond 24 Carat and Arctic MX-4 and the difference in temperatures were negligible. The important thing, though, is that you're running good temps now.
Speaking of IC Diamond thermal paste, has anyone used this brand before? It received a lot of good reviews so I thought I would try it out. The thing is, it is a LOT thicker/dense than most of the other pastes on the market. It comes out more like a glue substance rather than a paste. Is that how this paste usually is? Or did I just get a bad/old batch? The viscosity of it just feels so different from other pastes. Anyone know?