Depending on the processor, the manufacturer, how fast it runs, where the sensor is located, and what programs it is currently running will determine the temperature of what the processor should be. However, this document should give you a general idea of what the processor should be running at as well as what is acceptable and what is not.
The majority of today's desktop processors should not exceed temperatures of 95C and most will run between 70-90C.
Taken from:
What temperature should my processor be running at?