Active Coolers
Active coolers use small fans to generate additional airflow around the body of the laptop. This helps convect heat away from the device. Many cooler pads support the use of a power adapter, though they typically run on power drawn through one of the laptop's USB ports. Additionally, many cooler pads come with a built-in USB hub as not to consume one of the laptop's often limited number of USB ports.
Some active coolers draw heat from the underside of the computer; others work in the opposite way by blowing cool air towards the machine. The fan speed is adjusted manually or automatically on certain models and on others stays at a fixed speed.
Poorly designed coolers may use fans which draw more current than allowed by the USB standard. Without correct protection, such devices can cause damage to the USB power supply.
Inside the laptop, the USB power-supply has to output an additional amount of watts for the USB-powered fan, thus generating a small amount of additional heat. This additional heat generation is usually insignificant in relation to the amount of heat a fan moves away from the laptop.
Read more about this topic: Laptop Cooler
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