computer form factor

Computer Form Factor

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Computer Form Factor In computing, a form factor specifies the physical

dimensions of major system components.

Specifically, in the IBM PC compatible industry,

standard form factors ensure that parts are

interchangeable across competing vendors and

generations of technology, while in enterprise

computing, form factors ensure that server modules

fit into existing Rackmount systems.


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Computer Form Factor Traditionally, the most significant specification is

the motherboard, which generally dictates the

overall size of the case.

Small form factors have been developed and

implemented, but further reduction in overall size is

hampered by current power supply technology.


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Computer Case A computer case (also known as a computer

chassis, cabinet, box, tower, enclosure, housing,

system unit or simply case) is the enclosure that

contains most of the components of a computer

(usually excluding the display, keyboard and

mouse).


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Computer Case

A computer case is sometimes incorrectly

referred to as a CPU.

Cases are usually constructed from steel or

Aluminium.

Plastic and wood are sometimes used.


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Computer Case: Sizes Cases can come in many different sizes.

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.

Personal computer form factors 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.


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Rack Mounted Systems


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Blade Servers


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Computer Case: Sizes Case designed for an ATX motherboard and power

supply may take on several external forms:

Vertical Tower (Designed to sit on the floor, height

> width)

Flat Desktop (height < width)

Pizza Box (height ≤ 2 inches, designed to sit on the

desk under the computer's monitor).


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Computer Case: Sizes


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Computer Case: Sizes Tower cases come in mini-tower, mid-tower, and

big-tower/full-tower sizes.

Full tower cases are typically 22 inches or more in

height and intended to stand on the floor.

They have six to ten drive bays.


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Computer Case: Sizes Midtower cases are smaller, about 18" high with

two to four external bays.

Minitower case will typically have only one or two

external bays and stand from 14" to 16" tall.


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Computer Case: 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.


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Computer Case: Layout 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.


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Computer Case 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 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.


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Computer Case Major Component Locations:

• Most cases include drive bays on the front of the case; a

typical ATX case includes both 5.25" and 3.5" bays

• 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.


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Computer Case Internal access

• Tower cases have single side panel which may be

removed in order to access the internal components.

• Computer cases required screws to hold components and

panels in place (i.e. motherboard, PSU, drives, and

expansion cards).

• 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.


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Computer Case 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.

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computer form factor