Try this 1
Clean all the vents, blow out with canned air.
Remove the power adapter and the battery from your laptop. Open the laptop
case to access the CPU Fan and the heat sink. Remove all the dust from the Fan
and also from the heat sink. Never run your laptop on bag & bed. Sides, back and
bottom must be clear.
If possible remove the old thermal paste from the CPU and apply a new thermal
paste for better heat conductivity.