CPU Temperature sensor wrong?

If the fan is very cool and the processor is reporting very hot, I would first suspect the connection between the fan/heatsink and the processor package. Make sure the heatsink is properly seated with thermal paste.

Let's get some terminology straight from Lavalys' KB:

• CPU Diode or Core temperature is the temperature measured across a temperature sensitive diode on the processor die. The most common implementation uses a temperature sensor part external to the processor with the CPU Thermal Diode Anode (+) and Cathode (-) connections to it.
• CPU Temperature is the temperature measured by a remote temperature sensors part on the motherboard near the CPU.

It is possible for these temperature sensors to fail although I haven't seen it personally.

Try installing a different processor and see if the readings are still incorrect. This can help point to where the problem lies. If the readings are OK, I would suspect your processor, if they are off as well, then suspect the parts on the board.

Unfortunately, if it isn't the heatsink, there is no easy user fix other than replacing the offending part.

It could be a bad sensor, but I wouldn't wager on it. Check layer of conduction paste, seems like that could be the problem.

I had same overheating problem with intel i5-661 and ASUS P7H55M mobo. This has a push-fit heatsink and fan and one of the push-fit posts had come loose. PC was switching off at 93 celsius. Fixed push-fit retaining post for fan and normal operation at 46 celsius resumed.