Start by blowing compressed air through the vents to blow the dust out blow it both ways in and out the intake vents and output vents . Make sure you don't block the vents while using the laptop don't set it on a pillow or blanket while running . next try a laptop cooler and if none of this helps it may be time to reapply thermal paste between the cpu and the heat sink . while you have it torn apart to do this a through cleaning would be good. Check for popped capacitors and make sure the fan is running at the right speed. Hope this helps