SpeedFan 4.29
 

SpeedFan is a freeware program that monitors fan speeds, temperatures and voltages in computers with hardware monitoring chips. SpeedFan can even access S.M.A.R.T. info and show hard disk temperatures too, if supported.

Check out this addition:

* added full support for AMD K8 (Sempron, Opteron, Athlon 64) internal temperature sensor

try it out, you'll get a "core" temp readout in Speedfan which is a bit higher than the "old" CPU temp value

core temp rises quicker, reports higher temp and drops faster when CPU load is 0%

in the chart below CPU temp vs Core temp: