Acomputer case, also known as acomputer chassis, is theenclosure that contains most of thehardware of apersonal computer. The components housed inside the case (such as theCPU,motherboard,memory,mass storage devices,power supply unit and variousexpansion cards) are referred as theinternal hardware, while hardware outside the case (typicallycable-linked orplug-and-play devices such as thedisplay,speakers,keyboard,mouse andUSB flash drives) are known asperipherals.
Conventional computer cases are fully enclosed, with small holes (mostly in the back panel) that allowventilation and cutout openings that provide access toplugs/sockets (back) andremovable mediadrive bays (front). Thestructural frame (chassis) of a case is usually constructed from rigidmetals such assteel (oftenSECC — steel, electrogalvanized, cold-rolled, coil) andaluminium alloy, withhardpoints andthrough holes for mounting internal hardware,case fans/coolers and for organizingcable management. The external case panels, at least one of which are removable, cover the chassis from the front, sides and top to shield the internal components from physical intrusion anddust collection, and are typically made from painted metallic and/orplastic material, while other materials such asmesh,tempered glass,acrylic,wood and evenLego bricks have appeared in many modern commercial orhome-built cases. In recent years,open frame oropen air cases that are only partly enclosed (with freer ventilation and thus theoretically bettercooling) have become available in the premiumgaming PC market.
Cases can come in many different sizes and shapes, which are usually determined by theform factor of themotherboard since it is physically the largest hardware component in most computers. Consequently, personal computer form factors typically specify only theinternal dimensions and layout of the case. Form factors forrack-mounted andblade servers may include preciseexternal dimensions as well since these cases must themselves fit in specific enclosures.
For example, a case designed for anATX motherboard andpower supply unit (PSU) may take on several external forms such as a verticaltower (designed to sit on the floor, height > width), a flatdesktop (height < width) orpizza box (height ≤ 5 cm or 2 in) designed to sit on the desk under the computer'smonitor). Full-size tower cases are typically larger in volume than desktop cases, with more room fordrive bays,expansion slots, and custom or all-in-one (AIO) water cooling solutions. Desktop cases—andmini-tower cases under about 46 cm (18 in) high—are popular in business environments where space is at a premium.[1]
Currently, the most popular form factor for desktop computers is ATX,[citation needed] althoughmicroATX andsmall form factors have also become very popular for a variety of uses. In the high-end segment, the unofficial and loosely defined XL-ATX specification appeared around 2009. It extends the length of the mainboard to accommodate four graphics cards with dual-slot coolers. Some XL-ATX mainboards increase the mainboard's width as well, to allow more space for the CPU, 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). As of 2018, no major motherboard manufacturer has made an XL-ATX board for several years. E-ATX is similar to XL-ATX in that it is larger than ATX and is also loosely defined. Unlike XL-ATX, E-ATX motherboards and cases are still in production (as of 2020), and support quad-channel memory across 8 slots of ram, up to 4 PCI-e expansion slots for up to 4 double slot graphics cards and a single CPU such as the AMD Ryzen Threadripper 3990X.[2][3][4][5][6] Companies likeIn Win Development,Shuttle Inc. andAOpen originally popularized small cases, for whichFlexATX was the most common[dubious –discuss] motherboard size. As of 2010Mini ITX has widely replacedFlexATX as the most common small form factor mainboard standard. The latest mini ITX mainboards fromAsus,Gigabyte,MSI,ASRock,Zotac andFoxconn offer the same feature set as full size mainboards. High-end mini ITX mainboards support standard desktop CPUs, use standard memory DIMM sockets, and mostly feature a full-size PCI-E 16× slot with support for the fastest graphics cards, although some instead use a PCI, or PCIe slot of fewer than 16 lanes. This allows customers to build a fully-fledged high-end computer in a significantly smaller case.Apple Inc. has also produced theMac Mini computer, which is similar in size to a standard CD-ROM drive, and many manufacturers offer mini-ITX cases of similar size for low-wattage CPUs with integrated graphics.
Tower cases are often categorized as mini-tower, midi-tower, mid-tower, or full-tower. The terms are subjective and inconsistently defined by different manufacturers.
Full tower cases are typically 56 cm (22 in) or more in height and intended to stand on the floor. They can have anywhere from six to ten externally accessible drive bays. These cases were originally developed to housefile servers which would typically be tasked with serving data from expensive CD-ROM databases that held more data than the hard drives commonly available at the time. Hence, many full tower cases include locking doors and other physical security features to prevent theft of the discs. However, as computing technology moves fromfloppy disks andCD-ROMs to large capacity hard drives,USB flash drives, and network-based solutions, more recent full tower cases typically only have none, one, or two external bays for CD drives, with the internal bays moved elsewhere in the case to improve airflow. Today, full tower cases are commonly used by enthusiasts as showpiece display cases with custom water cooling, lighting, and tempered glass (replacing acrylic).[7][8][9] They may also hold two computers (as is the case with the Corsair 1000D) and dual power supplies (Corsair 900D).[10][11]
Mid-tower cases are smaller, about 46 cm (18 in) high with two to four external bays. They may also hold two computers.[12]
Amini-tower case will typically have only one or two external bays.[13]
The marketing termmidi-tower sometimes refers to cases smaller than mid-tower but larger than mini-tower, typically with two to three external bays.[14] Other times the term may be synonymous withmid-tower.[15]
Computer cases usually include sheet metal enclosures for apower supply unit anddrive bays, as well as a rear panel that can accommodateperipheral connectors protruding from the motherboard andexpansion slots. Most cases also have a power button or switch, areset button, andLEDs to indicate power, hard drive activity, and network activity in some models. Some cases include built-in I/O ports (such asUSB and headphone ports) on the front of the case. Such a case will also (normally) include the wires needed to connect these ports, switches, and indicators to the motherboard.[16]
Accessing the interior components of a modernATX tower case is done by removing the side panels. Looking front-to-back, accessing the motherboard, PSU, drive bays, and most case fan installation points are 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 may disrupt the flow of air within the case causing increased temperatures.[17]BTX, an uncontemporary standard, has the main side panel on the right side as opposed to the left. Some upside-down designed ATX cases are also accessed by removing the right-side panel door.
Alternatively, the case may have a single large U-shaped cover that saddles the chassis. This was ubiquitous inAT tower cases.
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 panels. If there is any doubt, consult the user's manual if possible.
Traditionally, most computer cases requiredcomputer case screws to hold components and panels in place (i.e. motherboard, PSU, drives, and expansion cards). From the early 2000s onwards 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.
Throughout the 1990s, most computer cases had simple rectangular shapes, and were often paintedbeige orwhite with little attention given to the visual design.Beige box designs are still found on a large number of budget computers assembled from generic components. These class of machines are now known aswhite box computers, even though the cases for these types of machines are now generally colored black or silver instead of beige. More modern computer cases include a much wider range of variation in shape, color, form factor, and materials, such as brushed aluminium and/or tempered glass which are offered with more expensive cases.
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 colored internal lighting, custom paint, orliquid cooling systems. Some hobbyists build custom cases from raw materials like aluminum, steel,styrofoam, acrylic, or wood.
Historically, cases used CCFL lighting[18] and eventually single color LEDs as strips or in fans to illuminate their interior; modern cases use RGB LED lighting instead, often incorporated into case fans. To improve airflow while allowing RGB fans to be visible, many cases as of 2020 use metal meshes, without any external bays.[19] Many include a PSU shroud and vertical gpu mounts. Some used to include holes to support external water cooling radiators.[20][21][22][23][24][25] Cases with side windows may have side fans (on the window) as well, although it is uncommon for cases with glass windows to have side fans.[26]
Prominentafter-market case manufacturers includeAntec,BitFenix,Cooler Master,Corsair,Fractal Design,In Win Development,Lian Li,NZXT Corp.,Phanteks,Rosewill, andThermaltake, (DIY PC)
Some computer cases include abiased 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'sfirmware orBIOS may be configured to report this event the next time it is powered on. This physicalintrusion detection system may help computer owners detect tampering with their computers. 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 (including full tower cases) intended to housefile servers featured alocking door covering the external drive bays. This was a security feature intended to prevent the theft of theCD-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.
