What I generally find with portables and desktops is over time, there eventually is a buildup of dust at the heatsink which blocks airflow. This is the biggest contributing factor to heat related issues. Airflow is literally choked. Cooler units won't prevent that. A little occasional preventive maintenance can go a long ways.
Commonly a portable will draw air from the bottom. Pass though the fan and then through the heatsink fins and exhaust out the rear or side of the portable. What I do with mine (power is off) is open a thin paper clip and poke it though one of the little holes as far as I can up into the fan. Then using canned air, blow through the exhaust to dislodge the dust buildup. Then blow air back in through the bottom real good. I do this a couple times generally. The paper clip prevents the fan from overspinning and getting damaged.
Portables may have more than one fan...one for the CPU and one for the Video.
Laptop Coolers can effectively reduce the overall heat you may feel from your laptop. But they lack the capacity to improve the internal airflow that must be maintained to prevent damage to the processor, and/or video chip.
A typical symptom of a blocked heatsink is that the processor fan runs unusually fast or noisily. Most office supply and computer stores sell canned air. for $5-$10 and works well for dusting off monitors and keyboards also. The propellant quickly evaporates and is totally safe to use on electronic equipment.