hmmm
they both could be right...
a friend has something similar, got a a7a266 board, and u can choose 3 temps, one is the mobo, the other two are cpu, but ones around 46 the other 54... both go up and down according to CPU load.
i think the 46 one is the 'real' reading, while the 54 is the corrected asus reading.
anyways, if your computer is stable and not crashing, u really dont have anything to worry about.
The lack of thermal protection on Athlon's is cunning way to stop morons from using AMD.