The internal components of the tower system unit are laid out vertically (as opposed to the desktop system). Among these components are the motherboard, fan, internal speaker, power inlet, expansion slots, disk drive (or drives, if any), power supply, chassis lock, and any additional cards such as memory, graphics, and sound.
The interior of the tower case is more spacious than that of the |desktop| chassis. Although containing the about the same number of expansion slots, the tower generally does have more disk drive bays. A common tower configuration is to have two |floppy disk drives| (one 3 1/2" and one 5 1/4"), and one |hard drive|. Often, an optical drive is included as well. The tower chassis is preferred if a greater number of disk drives will be needed.
