Computer case

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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 also known as a "computer chassis", "tower", "system unit", "base unit" or simply "case" and sometimes incorrectly referred to as the "CPU" or "hard drive",[1][2] 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[edit]

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 46 cm (18 in) high—are popular in business environments where space is at a premium.[3]

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 Mainboard's 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 ] 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. High-end 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.[4][5] This is a high-end case intended for desktop systems and doesn't include security features.

Layout[edit]

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[citation needed] and network activity (in some models). 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.

Major component locations[edit]

  • The motherboard is usually screwed to the case along its largest face, which could be the bottom or the side of the case depending on the form factor and orientation.
  • Form factors such as ATX provide a back panel with cut-out holes to expose I/O ports provided by integrated peripherals, as well as expansion slots which may optionally expose additional ports provided by expansion cards.
  • The power supply unit is often housed at the top rear of the case; it is usually attached with four screws to support its weight.
  • Most cases include drive bays on the front of the case; a typical ATX case includes both 5.25" and 3.5" bays. In modern computers, the former are used mainly for optical drives, while the latter are used for hard drives, floppy drives, and card readers.
  • Buttons and LEDs are typically located on the front of the case; some cases include additional I/O ports, temperature and processor speed monitors in the same area.
  • Vents are often found on the front, back, and sometimes on the side of the case to allow cooling fans to be mounted via surrounding threaded screw holes.

Internal access[edit]

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). From the 2000s there is a trend towards tool-less 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[edit]

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[edit]

Prominent after-market case manufacturers include Antec, AOpen, Chieftec, Cooler Master, Corsair, In Win Development, IXIUM, Lian Li, NZXT Corp., Shuttle Inc., SilverStone Technology, Thermaltake, iStarUSA Group and Zalman.

Intrusion detection[edit]

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[edit]

See also[edit]

References[edit]

  1. ^ Tadeo, Aaron (January 13, 2011). "The CPU Versus the Computer Tower Case". Yahoo! Voices. Yahoo!. Retrieved October 25, 2013. 
  2. ^ "Don’t call a computer a hard drive". One Technical. December 28, 2005. Retrieved October 25, 2013. 
  3. ^ "Reference Guide - Case - Styles". PCGuide. Retrieved 2013-09-28. 
  4. ^ "Cooler Master – Cosmos II". Cooler Master. Retrieved September 28, 3013. 
  5. ^ "CoolerMaster Cosmos II Ultra Tower Case Review". Overclockers. January 27, 2012. Retrieved September 28, 2013. 

External links[edit]