My XP1800 non-OC, running SETI on a MSI K7T Turbo seems to be locked in @ 52C, with a Taisol GCK7600092/Sunon Fan and AS-2.
I did forget to plug in the fan when I first installed, and the system lasted about 5 minutes.
I turned off immediately, and the HS darn near burned my fingers.
Anyway, plugged the fan in, and everything booted up. System seems to be humming along quite nicely.
As far as too much/not enough Thermal Compound, remember that you really only want enough to fill in the
minute crevices, and any surface differences due to convex/concave surfaces of the CPU & HS. So,
actually less can be better, as you really want as much bare metal on metal as possible.