Check the total power consumption of the fans against the rating of the power adapter you mention. The power consumption of one fan may be expressed in milliamps on the label.
Hi, I liked your precise answer to the person's query. I am using a single fan cooling pad purchased from the market but I feel it is running at a slow speed and my laptop heats up (does not shuts down but) considerably after using for long hours. Please advice how I may increase the speed of this fan. It draws power from USB port.