Examine individual changes

'[[Image:Stripped-computer-case.JPG|right|thumb|An [[ATX]] desktop case lying on its side, the rear closest to the camera. The motherboard will lie flat on the bottom, (which would be the right panel with the case upright). Peripheral connectors will protrude 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''', '''cabinet''', '''base unit''' or simply '''case''' and sometimes incorrectly referred to as the "CPU" or "hard drive",<ref name="CPU versus computer tower">{{cite web|last=Tadeo|first=Aaron|title=The CPU Versus the Computer Tower Case|url=http://voices.yahoo.com/the-cpu-versus-computer-tower-case-7745986.html?cat=15|work=[[Yahoo! Voices]]|publisher=[[Yahoo!]]|accessdate=October 25, 2013|date=January 13, 2011}}</ref><ref name="Computer is not hard drive">{{cite web|title=Don’t call a computer a hard drive|url=http://blog.onetechnical.com/2005/12/28/dont-call-a-computer-a-hard-drive/|work=One Technical|accessdate=October 25, 2013|date=December 28, 2005}}</ref> 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== {{further2|[[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 server|blade]] [[server (computing)|server]]s 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 form factor|pizza box]]'' (height ≤ {{convert|5|cm|in|0|abbr=on}}, designed to sit on the desk under the computer's [[computer monitor|monitor]]). Full-size tower cases are typically larger in volume than desktop cases, with more room for [[drive bay]]s and [[expansion slot]]s. Desktop cases&mdash;and ''mini-tower'' cases under about {{convert|18|in|cm|abbr=on|disp=flip}} high&mdash;are popular in business environments where space is at a premium.<ref>{{cite web|url=http://www.pcguide.com/ref/case/styles.htm |title=Reference Guide - Case - Styles |publisher=PCGuide |date= |accessdate=2013-09-28}}</ref> Currently, the most popular form factor for desktop computers is ATX, although microATX and [[small form factor]]s 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 [[Acer (company)|AOpen]] originally popularized small cases, for which [[FlexATX]] was the most common{{Dubious|date=November 2009}} 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 {{convert|56|cm|in|0|abbr=on}} 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 disk]]s and [[CD-ROM]]s to large capacity hard drives, [[USB flash drives]], and network-based solutions. The full tower case was developed to house [[file server]]s 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 theft of the discs. Midtower cases are smaller, about {{convert|46|cm|in|0|abbr=on}} high with two to four external bays. A minitower case will typically have only one or two external bays and stand from {{convert|36|cm|in|0|abbr=on}} to {{convert|41|cm|in|0|abbr=on}} tall. In 2012 [[CoolerMaster]] introduced the Cosmos II "ULTRA-Tower" case, standing {{convert|71|cm|in|0|abbr=on}} tall and featuring 16 drive bays.<ref name="Cosmos II">{{cite web|title=Cooler Master – Cosmos II|url=http://www.coolermaster.com/microsite/cosmos_ii/design.html|work=[[Cooler Master]]|accessdate=September 28, 2013}}</ref><ref name="Review">{{cite web|url=http://www.overclockers.com/coolermaster-cosmos-ii-ultra-tower-case-review |title=CoolerMaster Cosmos II Ultra Tower Case Review|work=Overclockers|date=January 27, 2012|accessdate=September 28, 2013}}</ref> 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 slot]]s. Most cases also have a power button or switch, a [[reset button]], and [[LED]]s to indicate power status as well as hard drive {{citation needed|date=December 2013}} 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=== * 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 port]]s provided by [[integrated peripheral]]s, as well as [[expansion slot]]s which may optionally expose additional ports provided by [[expansion card]]s. * The [[power supply unit]] mounting point differs from case to case, but the most commonly used locations (both at the rear of the case) and their benefits/disadvantages are: 1. The top of the case, usually allowing the PSU's built-in fan to act as an auxiliary exhaust fan, but causes the PSU to be fed air heated by the internal components of the case, thus causing PSU efficiency and lifespan degradation. 2. The bottom of the case, with a (often filtered) vent in the bottom of the case allowing the PSU to draw cool air from the outside. Regardless of the mounting position, the PSU will usually be attached to the case with four [[screw]]s to support its weight. * Most cases include [[drive bay]]s 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 drive]]s, while the latter are used for [[hard drive]]s, [[floppy drive]]s, and [[card reader]]s. * 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, top, left side panel, and sometimes on the right side panel of the case. Regardless of their placement, their purpose is either to let cool air into the case, or to let hot air out. Larger vents usually allow [[computer fan|cooling fans]] to be mounted via surrounding threaded screw holes. Newer cases include mountings for larger 120mm or 240mm cooling fans for quieter operation than the 80mm fans formerly common. ===Internal access=== Accessing the interior components of a modern tower case is done by removing the left side panel. Looking front-to-back, accessing the motherboard, PSU, drive bays and most case fan installation points is done by removing the left side panel. Removing the right side panel is done less often to access the space behind the motherboard mounting plate. This space is devoted to cable management, as cables routed in front of the motherboard will cause disruptions in the flow of air within the case. Alternatively, the case may have a single large U-shaped cover that saddles the chassis. To prevent the buildup of performance-degrading dust within the case, many models feature dust filters in front of the air intake fans. While the exact method of accessing the front filters depends on the case model, it usually requires the removal of the entire front panel. Removal of the front panel itself may or may not require the removal of one or both of the side panel. If there is any doubt, consult the user's manual if possible. 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, and is also cheaper to manufacture. ==Appearance== {{further2|[[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 (computer hardware)|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 [[Watercooling|liquid cooling system]]s. Some hobbyists build custom cases from raw materials like aluminum, steel, styrofoam, acrylic, or wood. ===Case manufacturers=== {{See also|List of computer hardware manufacturers#Computer cases}} Prominent [[after-market (general)|after-market]] case manufacturers include [[Antec]], [[BitFenix]], [[Cooler Master]], [[Corsair]], Fractal Design, [[In Win Development]], [[Lian Li]], [[NZXT Corp.]], [[Raidmax]], [[Rosewill]], and [[Thermaltake]]. == Intrusion detection == Some computer cases include a [[Momentary switch|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 server]]s featured a [[Round-key lock|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== <gallery caption="Computer cases" perrow="8"> Image:SWTPC6800 open.jpg|[[SWTPC|SWTPC 6800]] case with SS-50 and SS-30 buses—an early hobbyist machine Image:Cooler_Master_690_II_Advanced_Nvidia_Edition_Mid_Tower.jpg|Cooler Master 690 II Advanced Nvidia Edition mid tower case Image:Beige mini tower case.jpg|A beige mini tower case ([[microATX]] form factor) Image:ATXDesktop.jpeg|Micro ATX Desktop case beside standard ATX tower case Image:Modified-pc-case.png|Enthusiast case featuring translucent panel [[Case modding|casemod]] Image:Example of an Enthusiast's PC.jpg| NZXT Case showing an example of a modern Enthusiast case along with Power supplies and a CPU Fan. Image:Paris servers DSC00190.jpg|Three of the Wikimedia servers in [[rack unit|1U]] [[rackmount]] cases Image:Home theater PC front with keyboard.jpg|[[Antec]] Fusion V2 [[home theater PC]] case with [[Vacuum fluorescent display|VFD display]], volume control and some [[Computer port (hardware)|ports]] on front. Image:80486-Desktop-PC.jpg|8-slot [[Baby AT]] form factor case Image:Macpro.png|Mac Pro tower case. Note the two barely visible front intake fans. Image:Power Macintosh 9600 350.jpg|Power Mac tower case. Image:NeXTcube.jpg|NeXT Cube Image:SGI-indigo-front.jpg|SGI Indigo tower case Image:Silicon Graphics O2 Plus.jpg|SGI O2 tower case Image:IBM PC 5150 no monitor.jpg|[[IBM Personal Computer]] Image:IBM 5150 Casing.jpg|IBM Personal Computer 5150 bare 5-slot case Image:Ibm px xt color.jpg|[[IBM Personal Computer XT]] Image:Ibmcerrojo.jpg|[[IBM Personal Computer/AT]] Image:Traserapcat.jpg|IBM Personal Computer/AT Image:IBM PS2 MCA Model 55 SX, front.jpg|[[IBM Personal System/2]] Model 55SX Image:IBM PS2 MCA Model 55 SX, internal components overview.jpg|IBM Personal System/2 Model 55SX Image:IBM PS2 MCA Model 70, front view.jpg|IBM Personal System/2 Model 70 Image:IBM Model70 80386.JPG|IBM Personal System/2 Model 70 Image:DeuxPS2.jpg|IBM Personal System/2 Models 60 and 80 </gallery> ==See also== {{Commons category|Computer cases}} *[[3D printing]] *[[Computer case screws]] *[[List of computer hardware manufacturers]] *[[Novena (computing platform)|Novena]] *[[Thermally Advantaged Chassis]] *[[VIA OpenBook]] open case design standard. ==References== {{Reflist}} ==External links== * [http://www.formfactors.org/formfactor.asp Chassis Form Factors] {{Basic computer components}} [[Category:Computer enclosure]]'