last time i running t-birds 1.33ghz with coolermaster heat pipe and the idle temp is 55c and now i am running 2000xp with the same heat sink and temp also 55c on idle.why?as i know xp running cooler than t-birds
Heatpipes are 'set' to run at a certain temperature by the pressure inside of them. If they use water as the working fluid, then the lower the pressure (greater vacuum) the lower the temperature at which heatpipe starts to pump the heat up to the fins on the heatsink.
Changing one processor to another can't change the operating temperature of the heatpipe.
It sounds like yours begins working at around 40-50C. Others of the same brand might also have different temperatures because of variance in the manufacturing process creates different vacuum pressures inside the pipe.
If your heatsink is available locally, you might try trading it in on another one, claiming it leaked and lost some effectiveness, and try your luck with the new one that might operate at a lower temperature (thus keeping the processor at a lower temp).