It is advised to check the core temperatures of the cpu. Overclocking the cpu caused by any kind of background applications results in high cpu usage and thus temperature will get rosen over 80 degree Celsius.
1. Clean the fan, heat sink areas which might be covered with dust.
2. Inspect the thermal paste condition. ( sometimes the thermal past might get dried up resulting in lower heat transfer. its better to clean the surface and reapply thermal paste)
3. make sure you have enough air circulation beneath the laptop. placing the laptop over any non uniform surfaces eg, over bed, couch etc.