Could this be the reason why it is getting so hot? Or is this temperature normal for the Q6600?
Temperatures on mine are 3°C lower than yours; I used a very thin layer of AS5 and it had a few years to cure. Core #0 runs a couple degrees warmer and that's normal. You provided Core temperatures, but what is the ambient room temperature (my room is at 23°C). Maximum temperature is reached within a few minutes and it won't get more than one or two degrees higher after 12 hours or more of Prime95.
Edit: It isn't hot enough to worry about it.