http://www.silentpcreview.com/article191-page1.html
"Calibrate Your CPU Temp Reporting"
"4. This article contains very little original thought. Nearly everything in here is based on the work of someone else, or upon commonly understood principles that have been explained elsewhere, often in much greater detail. This methodology is a distillation of these ideas into a single convenient place. If the subject interests you, I encourage you to do more reading elsewhere. Some excellent places to start are be the articles by Derek Peak (aka pHaestus) at Procooling.com: Reading from AMD's Thermal Diode, and Fun with AMD Diodes: CPU Mutilation, calibration and testing. Another important source is the useful, if obscure Calibrating the Internal Thermal Diode in an Intel PIII CPU at Arctic Silver."