Tuesday, November 25, 2008
Computer case
A computer case (also known as the computer chassis, cabinet, tower, box, enclosure, housing or simply case) is the enclosure that contains the main components of a computer. It has also been erroneously called the CPU, however this is an entirely different component. Cases are usually constructed from steel (often SECC - Steel, Electrogalvanized, Cold-rolled, Coil), aluminium, or plastic, although other materials such as wood and plexiglas have also been used in case designs.
Sizes
Cases can come in many different sizes, or form factors. The size and shape of a computer case is usually determined by the form factor of motherboard that it is designed to accommodate, since this is the largest and most central 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) or a flat desktop or pizza box (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 designed for the reduced microATX form factor—are popular in business environments where space is at a premium.
Currently, the most popular form factor for desktop computers is ATX, although microATX and small form factors have become very popular for a variety of uses. Companies like Shuttle Inc. and AOpen have popularized small cases, for which FlexATX is the most common motherboard size. Apple Computer has also produced the Mac Mini computer, which is similar in size to a standard CD-ROM drive.
There are mini-tower, midi-tower, big-tower/full-tower. Full tower cases are typically 30 inches or more in height and meant to stand on the floor. They have anywhere from 6-10 externally accessible drive bays with more internal-only. The ratio of external to internal bays is shifting however, as computing technology moves from floppy disks and CD-ROM to large capacity hard drives and network-based solutions. Midtower cases are smaller, about 24" high with 2-4 external bays. A minitower case will typically have only 1 or 2 external bays and stand from 12" to 18" tall.
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) or a flat desktop or pizza box (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 designed for the reduced microATX form factor—are popular in business environments where space is at a premium.
Currently, the most popular form factor for desktop computers is ATX, although microATX and small form factors have become very popular for a variety of uses. Companies like Shuttle Inc. and AOpen have popularized small cases, for which FlexATX is the most common motherboard size. Apple Computer has also produced the Mac Mini computer, which is similar in size to a standard CD-ROM drive.
There are mini-tower, midi-tower, big-tower/full-tower. Full tower cases are typically 30 inches or more in height and meant to stand on the floor. They have anywhere from 6-10 externally accessible drive bays with more internal-only. The ratio of external to internal bays is shifting however, as computing technology moves from floppy disks and CD-ROM to large capacity hard drives and network-based solutions. Midtower cases are smaller, about 24" high with 2-4 external bays. A minitower case will typically have only 1 or 2 external bays and stand from 12" to 18" tall.
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 a power button or switch, a reset button, and LEDs to indicate power status, hard drive usage, 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 wires needed to connect these ports to the motherboard.
Major component locationsThe motherboard is usually screwed to 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/or 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
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 screws to hold components and panels in place (i.e. motherboard, PSU, drives, and expansion cards). Recently 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.
Major component locationsThe motherboard is usually screwed to 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/or 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
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 screws to hold components and panels in place (i.e. motherboard, PSU, drives, and expansion cards). Recently 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
Through the 1990s, most computer cases had simple rectangular shapes, and were often painted beige. Beige box designs are still found on a large number of budget computers assembled from generic components.
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, acrylic, or wood.
Brands
Prominent after-market case manufacturers include Ahanix, Antec, AOpen, Chieftec, Cooler Master, Ever Case, Foxconn, Gigabyte Technology, HEC Compucase, IXIUM, Lian Li,CIRCLE,ODYSSEY,ZEBRONICS, NZXT, OrigenAE, Raidmax, Shuttle Inc., SilverStone Technology, Thermaltake and Zalman.
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, acrylic, or wood.
Brands
Prominent after-market case manufacturers include Ahanix, Antec, AOpen, Chieftec, Cooler Master, Ever Case, Foxconn, Gigabyte Technology, HEC Compucase, IXIUM, Lian Li,CIRCLE,ODYSSEY,ZEBRONICS, NZXT, OrigenAE, Raidmax, Shuttle Inc., SilverStone Technology, Thermaltake and Zalman.
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