An
ATX desktop case. The motherboard will lie flat on the bottom, against the right panel, with peripheral connectors protruding through the rear panel, drive bays at the top and front, and the power supply at the top and rear.
A computer case is also known as a "computer chassis", "tower", "system unit", "base unit" or simply "case". Also sometimes incorrectly referred to as the "CPU" or "hard drive", it is the enclosure that contains most of the components of a computer (usually excluding the display, keyboard and mouse).
Cases are usually constructed from steel (often SECC — Steel, electrogalvanized, cold-rolled, coil) or aluminium. Plastic is sometimes used, and other materials such as glass, wood and even Lego blocks have appeared in home-built cases.
Sizes
Further information: Comparison of computer form factors
Cases can come in many different sizes (known as form factors). The size and shape of a computer case is usually determined by the form factor of the motherboard, since it is the largest component of most computers. Consequently, personal computer form factors typically specify only the internal dimensions and layout of the case. Form factors for rack-mounted and blade servers may include precise external dimensions as well, since these cases must themselves fit in specific enclosures.
For example, a case designed for an ATX motherboard and power supply may take on several external forms, such as a vertical tower (designed to sit on the floor, height > width) or a flat desktop (height < width) or pizza box (height ≤ 5 cm (2 in), designed to sit on the desk under the computer's monitor). Full-size tower cases are typically larger in volume than desktop cases, with more room for drive bays and expansion slots. Desktop cases—and mini-tower cases under about 18 inches high—are popular in business environments where space is at a premium.[1]
Currently, the most popular form factor for desktop computers is ATX, although microATX and small form factors have also become very popular for a variety of uses. In the high-end segment the unofficial and loosely defined XL-ATX spec appeared around 2009. XL-ATX extends the length of the Mainboard to accommodate 4 graphics cards with dual-slot coolers. Some XL-ATX mainboards increase the Mainboards width as well, to allow more space for the CPU and Memory PWM, and in some cases a second CPU socket. While the market share of these exotic high-end mainboards is very low, almost all high-end cases and many mainstream cases support XL-ATX (10 expansion slots). Companies like In Win Development, Shuttle Inc. and AOpen originally popularized small cases, for which FlexATX was the most common[dubious – discuss] motherboard size. As of 2010 mini ITX has widely replaced FlexATX as the most common small form factor Mainboard standard. The latest mini ITX mainboards from Asus, Gigabyte, Zotac and Foxconn offer the same feature set as Full size Mainboards. Highend mini ITX mainboards support standard desktop CPUs, use standard memory DIMM sockets and feature a full size pciE 16x slot with support for the fastest graphics cards. This allows customers to build a fully fledged high-end computer in a significantly smaller case. Apple Inc. has also produced the Mac Mini computer, which is similar in size to a standard CD-ROM drive.
Tower cases are often categorized as mini-tower, mid-tower or full-tower. Full tower cases are typically 56 cm (22 in) or more in height and intended to stand on the floor. They have anywhere from six to ten externally accessible drive bays. The ratio of external to internal bays is shifting, however, as computing technology moves from floppy disks and CD-ROMs to large capacity hard drives, USB flash drives, and network-based solutions. The full tower case was developed to house file servers which would typically be tasked with serving data from expensive CD-ROM databases which held more data than the hard drives commonly available. Hence many full tower cases include locking doors and other physical security features to prevent the theft of the discs. Midtower cases are smaller, about 46 cm (18 in) high with two to four external bays. A minitower case will typically have only one or two external bays and stand from 36 cm (14 in) to 41 cm (16 in) tall. In 2012 CoolerMaster introduced the Cosmos II "ULTRA-Tower" case, standing 71 cm (28 in) tall and featuring 16 drive bays.[2][3][4][5] This is a high-end case intended for desktop systems and doesn't include security features.
Layout
Computer cases usually include sheet metal enclosures for a power supply unit and drive bays, as well as a rear panel that can accommodate peripheral connectors protruding from the motherboard and expansion slots. Most cases also have a power button or switch, a reset button, and LEDs to indicate power status as well as hard drive and network activity. Some cases include built-in I/O ports (such as USB and headphone ports) on the front of the case. Such a case will also include the wires needed to connect these ports, switches and indicators to the motherboard.
Internal access
Tower cases have either a single side panel which may be removed in order to access the internal components or a large cover that saddles the chassis. Traditionally, most computer cases required computer case screws to hold components and panels in place (i.e. motherboard, PSU, drives, and expansion cards). Recently[when?] there is a trend toward "screwless" cases, in which components are held together with snap-in plastic rails, thumbscrews, and other methods that do not require tools; this facilitates quick assembly and modification of computer hardware.
Appearance
Further information: Case modding
Through the 1990s, most computer cases had simple rectangular shapes, and were often painted beige or white with little attention given to visual design. Beige box designs are still found on a large number of budget computers assembled from generic components. This class of machines is still known as white box computers.
Case modding is the artistic styling of computer cases, often to draw attention to the use of advanced or unusual components. Since the early 2000s, some cases have included clear side panels or acrylic windows so that users can look inside while it is operating. Modded cases may also include internal lighting, custom paint, or liquid cooling systems. Some hobbyists build custom cases from raw materials like aluminum, steel, styrofoam, acrylic, or wood.
Case manufacturers
See also: List_of_PC_hardware_manufacturers#Com puter_cases
Prominent after-market case manufacturers include Antec, AOpen, Chieftec, Cooler Master, Corsair, In Win Development, IXIUM, Lian Li, NZXT, Shuttle Inc., SilverStone Technology, Thermaltake, iStarUSA Group, Zalman.
Intrusion detection
Some computer cases include a biased switch (push-button) which connects to the motherboard. When the case is opened, the switch position changes and the system records this change. The system's firmware or BIOS may be configured to report this event the next time it is powered on.
This physical intrusion detection system may help computer owners detect tampering with their computer. However, most such systems are quite simple in construction; a knowledgeable intruder can open the case or modify its contents without triggering the switch.
In the past, many tower cases intended to house file servers featured a locking door covering the external drive bays. This was a security feature intended to prevent the theft of the CD-ROM discs the drives would be holding. At the time, CD-ROM capacity was larger than the hard disks available, and many business-critical databases were distributed on this media. These databases were often very expensive or held proprietary data, and hence would be likely targets for casual theft.
Gallery
- Computer cases
A black mid tower case (ATX form factor)
A beige mini tower case (microATX form factor)
Micro ATX Desktop case beside standard ATX tower case
Enthusiast case featuring translucent panel casemod
NZXT Case showing an example of a modern Enthusiast case along with Power supplies and a CPU Fan.
8-slot Baby AT form factor case
IBM Personal Computer 5150 bare 5-slot case
IBM Personal System/2 Model 55SX
IBM Personal System/2 Model 55SX
IBM Personal System/2 Model 70
IBM Personal System/2 Model 70
IBM Personal System/2 Models 60 and 80
See also
- Computer case screws
- List of computer hardware manufacturers
- Thermally Advantaged Chassis
References
External links
