Do not remove the side panel of your computer to cool your PC

Actually by doing that you cause more heat inside. Why? Because your computer desktop's case is designed for something called airflow. It is this airflow that cools your computer and not just the dispelling of hot air by the fans. So one is naturally inclined to think that by opening the side panel and exposing the hot components to less warm air on the outside of the case the components will be cooler but that is not the case. Only when the case is properly enclosed you promote airflow. Your case might have come with one, two or more fans. Remember you were taught how hot air rises up. The fan(s) at the top of the case dispell this hot air through vents in the case. And as hot air rises up the components are cooled inside the case. In some cases there are additional fans on the side panel and most importantly at the bottom. This bottom fan pushes the hot air even faster to the top of the case. So with the side panel left open the fan at the bottom and the fan on the side are rendered almost useless. This is another reason why even the temporary slots for adding audio/video cards on the sides of the PC are provided with those removable metal plates. In the absence of these cards even these slots are to be kept closed.

There are a number of temperature checking programs that tell you the temperatures of the CPU, GPU, Hard Disk etc. Run the program and monitor temperatures of components both with the side panel open and with the side panel closed. You will see the difference.