I have this card, based on the X800 Radeon. Prob is, as soon as it is asked to do ANY 3D, it fries

Already at 77C when idle/passive, 3D, INSTANTLY (more or less) maxes out at 128C and then crash/reset.
These temps are from ATI tool, the only thing I can find to read temps from the GPU. The heatsink does not get too hot to the touch????

It has a passive "Silent Pipe" Cooler. Does anyone know how to safely take off the cooler? (I am thinking to reapply thermal paste as a first step)?