heatsink CPU temperature troubleshooting techniques

1. The heatsink was cleaned with an oil based cleaner which filled the microscopic gaps and contaminated the interface. 

2. The existing thermal interface material was not completely removed. The compound should be the only material between the heatsink and the CPU. 

3. The heatsink was not installed properly. 

4. The thermal compound was applied too thick. 

5. The measurement is being taken on the cold side of the thermal junction or on the side of the core where thermal compound squeezed from the junction contaminates the probe. (Better compound then transfers more heat to the probe so the temperature reads higher.) 

6. The measurement probe moved when the chip was removed to clean off the previous compound. 

7. The compound was not allowed to go through its break-in period. (Minimum 25 hours. Can be 400+ hours.) Temperatures will drop 1C to 5C over this time. 

8. The application was contaminated with an eyelash, a bit of dirt, fingerprint or something else that spaced the heatsink away from the metal cap. 

9. An unbalanced heatsink fan is causing excessive vibration and damaging the interface layer. 
10. An improperly manufactured or bent shim is interfering with proper contact between the CPU core and the heatsink. 

11. The heatsink fan was not plugged back in after the compound was changed. 

12. The ambient temperature where the computer is located has changed. If the room temperature changes, the CPU temperature will also change. It is important to remember that cooling solutions keep the CPU X number of degrees above ambient. So if the ambient temperature increases 3 degrees, the CPU temperature will also increase 3 degrees.