The box or outer shell that houses most of the computer, the system case is usually one of the most overlooked parts of the PC. While it may seem inconsequential, the case actually performs several important functions for your PC, including protection for the computer circuits, cooling, and system organization. In addition, the system case is normally purchased together with the system power supply, and must also be matched with the size, shape and electrical requirements of your motherboard. Therefore, it has an impact on your options with these important components as well.