A computer tower is the basic physical enclosure for modular computer systems used for desktop workstations and for servers with less than the highest performance or density requirements. Notebook/laptop computers, as well as embedded computers, are not usually considered modular; reconfiguration often requires a "forklift upgrade" of a total replacement.
Towers come with connectors and internal wiring, at a minimum, for a motherboard, power supply (computer), disk bays, cooling fan (computer) and possibly additional cooling components, and peripheral cards. They usually have standard connectors, on the main part of the chassis, for standard keyboard, video and mouse interfaces, as well as common external peripheral interfaces such as Universal Serial Bus and network interfaces such as Ethernet. Not all towers are compatible with all form factors for motherboards, disks, and peripherals. If additional monitors, for example, are needed, the additional video connectors may need to be on peripheral cards, or selected with a KVM switch.
They are taller than they are wide, although some can be turned 90 degrees and used horizontally. Horizontal mounting (as distinct from blade servers) may be more compact and more compatible with use in home entertainment systems, but be absolutely sure that placing the case horizontally does not block input or output air vents. Towers come in three basic forms:
- micro or mini tower: cheapest and most space-efficient; may be very limited in expansion capability
- mid tower: common compromise, but may still present challenges to upgrading in place
- full tower: easiest to access components, contain more components, and may have better cooling; most likely to accommodate all form factors