Everything outside of your computer is protected from noise created by the components inside the box, and electrical interference as well. You'll also have peripherals and drives failing months or years before they do on your friend's computer, and you'll never even dream that poor cooling is the cause. Making sure your system is cooled properly is one good way to save yourself time, trouble and money. Computer cases used by Steve Henes Computer Support have more cooling than any computer you can find in a retail outlet. All have well positioned cooling vents and at least two additional cooling fans strategically placed on the case to provide unparalleled cooling.
Small cases require components to be packed close together, which worsens cooling in two ways.
First, air flow through the case is reduced because it is blocked by the components. The case is key to a physical system organization that makes sense. If you want to add a hard disk, CD-ROM, tape backup or other internal device to your PC, the case is where it goes. If your case is poorly designed or too small, your upgrade or expansion options will be limited. The system case is what people see when they look at your computer.