Small form factor
Encyclopedia
A small form factor is a computer form factor designed to minimize the volume
of a desktop computer
. For comparison purposes, the size of an SFF case is usually measured in litre
s. SFFs are available in a variety of sizes and shapes, including shoeboxes, cubes, and book-sized PCs. Their smaller and often lighter construction has made them popular as home theater PC
s and as gaming computer
s for attending LAN parties. Manufacturers also emphasize the aesthetic and ergonomic design of SFFs since users are more likely to place them on top of a desk or carry them around.
Small form factors do not include computing devices that have traditionally been small, such as embedded
or mobile
systems. However, "small form factor" lacks a normative
definition and is consequently open to interpretation and misuse. Manufacturers often provide definitions that serve the interests of their products.
SFF originally referred to systems smaller than the Micro-ATX. The term SFF is used in contrast with terms for larger systems such as "mini-towers" and "desktops."
s, but in a smaller space. Most accept standard x86 microprocessors, standard DIMM
memory modules, standard 3.5 inch hard disk
s, and standard 5.25 inch optical drives.
However, the small size of SFF cases may limit expansion options; many commercial offerings provide only one 3.5" drive bay
and one or two 5.25" external bays. Standard CPU heatsinks do not always fit inside an SFF computer, so some manufacturers provide custom cooling
systems. Though limited to one or two expansion card
s, a few have the space for 3/4-length cards such as the GeForce GTX-295 Most SFF computers use highly integrated motherboards containing many on-board peripherals, reducing the need for expansion cards.
Even if labeled "SFF," cube-style cases that support full-sized (PS2 form factor) power supplies actually have a microATX form factor. True SFF systems use TFX or smaller power supplies, and some require a notebook-PC style external "power brick."
Some SFF computers even include compact components designed for mobile computer
s, such as notebook optical drives, notebook memory modules, notebook processors, and external AC adapters, rather than the internal power supply units found in full-size desktop computers.
Many SFF computers have a cubic shape. Smaller models are typically sold as barebones
units, including a case, motherboard, and power supply designed to fit together. The motherboard lies flat against the base of the case. Upgrade options may be limited by the non-standard motherboards, cramped interior space, and power and airflow concerns. The Apple Macintosh Cube
, released in 2000, and the Shuttle XPC are good examples of this design. MSI
and Asus
produce similar designs. The Xi3 Modular computer is an example of a cube computer with a little more upgrade possibilities.
AOpen Inc.
produced a stackable S120 case, allowing the user to stack up to four components vertically or horizontally. These layers can be for add-on cards, optical drives, and hard drives, using either internal power supplies or external AC adapter power sources. After the S120, AOpen made more small form factor cases for systems with Micro ATX and Mini-ITX.
Until recently, SFF cases were usually sold as barebones units (case, power supply, and motherboard) to system integraters and home-based builders. In 2005, Apple Inc. introduced its Mac Mini
(volume of 1.4 L
, excluding external power brick). Later in the same year, the first AOpen mini PC MP915 (renamed to XC mini in 2007 since “mini PC” could not be registered as a trademark), was announced. The size of the XC mini series PC — 165(W) × 50(H) × 165(D) mm — makes it one of the smallest desktop PC systems (1.3L volume). It was criticized for looking like the Apple Mac Mini, but Apple has not taken action on this subject. In February 2007, AOpen redesigned the case of the mini PC MP945 series.
, major OEM
PC brands such as HP and Dell
have begun to sell fully assembled SFF systems. These are often described as bookshelf units since they resemble a miniature tower case small enough to fit on a bookshelf. The HP Slimline series and Dell C521 (volume 1.65 L) are good examples of this trend. The Maxdata Favorite 300XS is another mini computer.
The HP Slimline uses a non-standard motherboard that is very similar in size to Mini-ITX.
In addition to its industrial use, the extremely small Mini-ITX
motherboard form factor has also been incorporated into SFF computers. These are often extremely compact, incorporating low-power components such as the VIA C3
processors. The Travla C134 is an example of this design; it is somewhat larger than the Mac mini (7×10×2" vs 6.5×6.5×2"), and barely bigger than a standard 5.25" optical drive.
or below in use). These devices are called nettops and include devices as Zonbu
, fit-PC
, Linutop
, and A9home
. With the release of Intel ATOM
CPU, AOpen also made Nettop systems: the uBox series with model LE200 and LE210. The uBox series equips a dual core Intel Atom 270/330 processor, single channel DDR-II 533/667 memory, Intel 945GC+ICH7 chipset, three SATA connectors and 5.1channel high definition audio output.
or mini audio receiver. The front panel interface is emphasized, with the optical disc drive rotated relative to the case in order to maintain horizontal mounting, and more motherboard port connectors (such as for USB) are routed to the front panel.
(COM) is a complete computer
built on a single circuit board. They are often used as embedded system
s due to their small physical size and low power consumption. Gumstix
is one example of a manufacturer of COMs.
Volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....
of a desktop computer
Desktop computer
A desktop computer is a personal computer in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Early desktop computers are designed to lay flat on the desk, while modern towers stand upright...
. For comparison purposes, the size of an SFF case is usually measured in litre
Litre
pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...
s. SFFs are available in a variety of sizes and shapes, including shoeboxes, cubes, and book-sized PCs. Their smaller and often lighter construction has made them popular as home theater PC
Home theater PC
A Home Theater PC or Media Center appliance is a convergence device that combines some or all the capabilities of a personal computer with a software application that supports video, photo, music playback, and sometimes video recording functionality...
s and as gaming computer
Gaming computer
A gaming computer is a personal computer that is capable of playing computationally demanding video games. Gaming computers are very similar to conventional PCs, with the main difference being the addition of a performance-oriented video card. Gaming computers are often associated with enthusiast...
s for attending LAN parties. Manufacturers also emphasize the aesthetic and ergonomic design of SFFs since users are more likely to place them on top of a desk or carry them around.
Small form factors do not include computing devices that have traditionally been small, such as embedded
Embedded system
An embedded system is a computer system designed for specific control functions within a larger system. often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal...
or mobile
Mobile computing
Mobile computing is a form of human–computer interaction by which a computer is expected to be transported during normal usage. Mobile computing has three aspects: mobile communication, mobile hardware, and mobile software...
systems. However, "small form factor" lacks a normative
Normative
Normative has specialized contextual meanings in several academic disciplines. Generically, it means relating to an ideal standard or model. In practice, it has strong connotations of relating to a typical standard or model ....
definition and is consequently open to interpretation and misuse. Manufacturers often provide definitions that serve the interests of their products.
History
The acronym SFF originally stood for "Shuttle Form Factor," describing shoebox-sized personal computers with two expansion slots. The meaning of SFF evolved to include other, similar PC designs from brands such as AOpen and First International Computer, with the word "Small" replacing the word "Shuttle".SFF originally referred to systems smaller than the Micro-ATX. The term SFF is used in contrast with terms for larger systems such as "mini-towers" and "desktops."
Features
Small form factor computers are generally designed to support the same features as modern desktop computerDesktop computer
A desktop computer is a personal computer in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Early desktop computers are designed to lay flat on the desk, while modern towers stand upright...
s, but in a smaller space. Most accept standard x86 microprocessors, standard DIMM
DIMM
A DIMM or dual in-line memory module, comprises a series of dynamic random-access memory integrated circuits. These modules are mounted on a printed circuit board and designed for use in personal computers, workstations and servers...
memory modules, standard 3.5 inch hard disk
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
s, and standard 5.25 inch optical drives.
However, the small size of SFF cases may limit expansion options; many commercial offerings provide only one 3.5" drive bay
Drive bay
A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed....
and one or two 5.25" external bays. Standard CPU heatsinks do not always fit inside an SFF computer, so some manufacturers provide custom cooling
Computer cooling
Computer cooling is required to remove the waste heat produced by computer components, to keep components within their safe operating temperature limits.Various cooling methods help to improve processor performance or reduce the noise of cooling fans....
systems. Though limited to one or two expansion card
Expansion card
The expansion card in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard or backplane to add functionality to a computer system via the expansion bus.One edge of the expansion card holds the contacts that fit exactly into the slot...
s, a few have the space for 3/4-length cards such as the GeForce GTX-295 Most SFF computers use highly integrated motherboards containing many on-board peripherals, reducing the need for expansion cards.
Even if labeled "SFF," cube-style cases that support full-sized (PS2 form factor) power supplies actually have a microATX form factor. True SFF systems use TFX or smaller power supplies, and some require a notebook-PC style external "power brick."
Some SFF computers even include compact components designed for mobile computer
Mobile computing
Mobile computing is a form of human–computer interaction by which a computer is expected to be transported during normal usage. Mobile computing has three aspects: mobile communication, mobile hardware, and mobile software...
s, such as notebook optical drives, notebook memory modules, notebook processors, and external AC adapters, rather than the internal power supply units found in full-size desktop computers.
SFF Types
The many different types of SFFs are categorized loosely by their shape and size. The ones below are available as of 2008.Cubic
Barebone computer
A barebone computer is a partially assembled platform or an unassembled kit of computer parts allowing more customization and lower costs than a retail computer system. They are available for desktop computer, notebook and server purposes, and in nearly any form factor...
units, including a case, motherboard, and power supply designed to fit together. The motherboard lies flat against the base of the case. Upgrade options may be limited by the non-standard motherboards, cramped interior space, and power and airflow concerns. The Apple Macintosh Cube
Power Mac G4 Cube
The Power Mac G4 Cube was a small form factor Macintosh personal computer from Apple Inc. It was sold from 2000 to 2001. Its cube shape is reminiscent of the NeXTcube from NeXT, acquired by Apple in 1996. The machine was designed by Apple industrial designer Jonathan Ive...
, released in 2000, and the Shuttle XPC are good examples of this design. MSI
Micro-Star International
Micro-Star International Co., Ltd is a Taiwan-based electronics company and one of the world's largest motherboard and video card manufacturers.-Overview:MSI is one of the top three motherboard and video card manufacturers worldwide...
and Asus
ASUS
ASUSTeK Computer Incorporated is a multinational computer technology and consumer electronics product manufacturer headquartered in Taipei, Taiwan. Its product range includes motherboards, desktops, laptops, monitors, tablet PCs, servers and mobile phones...
produce similar designs. The Xi3 Modular computer is an example of a cube computer with a little more upgrade possibilities.
AOpen Inc.
AOpen
AOpen is a major electronics manufacturer from Taiwan that makes computers and parts for computers. AOpen used to be the Open System Business Unit of Acer Computer Inc. which designed, manufactured and sold computer components. It incorporated in December 1996 as a subsidiary of Acer Group with an...
produced a stackable S120 case, allowing the user to stack up to four components vertically or horizontally. These layers can be for add-on cards, optical drives, and hard drives, using either internal power supplies or external AC adapter power sources. After the S120, AOpen made more small form factor cases for systems with Micro ATX and Mini-ITX.
Mini
Mac Mini
The Mac Mini is a small form factor desktop computer manufactured by Apple Inc. Like earlier mini-ITX PC designs, it is uncommonly small for a desktop computer: 7.7 inches square and 1.4 inches tall. It weighs 2.7 pounds...
(volume of 1.4 L
Litre
pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...
, excluding external power brick). Later in the same year, the first AOpen mini PC MP915 (renamed to XC mini in 2007 since “mini PC” could not be registered as a trademark), was announced. The size of the XC mini series PC — 165(W) × 50(H) × 165(D) mm — makes it one of the smallest desktop PC systems (1.3L volume). It was criticized for looking like the Apple Mac Mini, but Apple has not taken action on this subject. In February 2007, AOpen redesigned the case of the mini PC MP945 series.
, major OEM
Original Equipment Manufacturer
An original equipment manufacturer, or OEM, manufactures products or components that are purchased by a company and retailed under that purchasing company's brand name. OEM refers to the company that originally manufactured the product. When referring to automotive parts, OEM designates a...
PC brands such as HP and Dell
Dell
Dell, Inc. is an American multinational information technology corporation based in 1 Dell Way, Round Rock, Texas, United States, that develops, sells and supports computers and related products and services. Bearing the name of its founder, Michael Dell, the company is one of the largest...
have begun to sell fully assembled SFF systems. These are often described as bookshelf units since they resemble a miniature tower case small enough to fit on a bookshelf. The HP Slimline series and Dell C521 (volume 1.65 L) are good examples of this trend. The Maxdata Favorite 300XS is another mini computer.
The HP Slimline uses a non-standard motherboard that is very similar in size to Mini-ITX.
In addition to its industrial use, the extremely small Mini-ITX
Mini-ITX
Mini-ITX is a 17 x 17 cm low-power motherboard form factor developed by VIA Technologies in 2001. Mini-ITX is slightly smaller than microATX. Mini-ITX boards can often be passively cooled due to their low power consumption architecture, which makes them useful for home theater PC systems,...
motherboard form factor has also been incorporated into SFF computers. These are often extremely compact, incorporating low-power components such as the VIA C3
VIA C3
The VIA C3 is a family of x86 central processing units for personal computers designed by Centaur Technology and sold by VIA Technologies. The different CPU cores are built following the design methodology of Centaur Technology.-Samuel 2 and Ezra cores:...
processors. The Travla C134 is an example of this design; it is somewhat larger than the Mac mini (7×10×2" vs 6.5×6.5×2"), and barely bigger than a standard 5.25" optical drive.
Nettop
, several other companies have released other very small computers that besides a small size, focus on a low price, and extremely high power efficiency (typically 10 WWatt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
or below in use). These devices are called nettops and include devices as Zonbu
Zonbu
Zonbu is a technology company that sells a computing platform which combines a web-centric service, a small form factor PC, and an open source based software architecture...
, fit-PC
Fit-PC
The fit-PC is a small, light, fan-less nettop computer manufactured by the Israeli company CompuLab.Three fit-PC models are available - fit-PC 1.0 was introduced in July 2007, fit-PC Slim was introduced in September 2008, and fit-PC 2 was introduced in May 2009...
, Linutop
Linutop
The Linutop is a small, light, environment friendly nettop computer with a metal case, no moving parts, and running the Linutop OS , a customized version of Linux based on the Xubuntu then Ubuntu/GNOME distribution....
, and A9home
A9Home
The A9Home is a small form factor desktop computer running RISC OS Adjust32. It was officially unveiled at the 2005 Wakefield Show, and is the second commercial ARM based RISC OS computer to run a 32-bit version of RISC OS...
. With the release of Intel ATOM
Intel Atom
Intel Atom is the brand name for a line of ultra-low-voltage x86 and x86-64 CPUs from Intel, designed in 45 nm CMOS and used mainly in netbooks, nettops, embedded application ranging from health care to advanced robotics and Mobile Internet devices...
CPU, AOpen also made Nettop systems: the uBox series with model LE200 and LE210. The uBox series equips a dual core Intel Atom 270/330 processor, single channel DDR-II 533/667 memory, Intel 945GC+ICH7 chipset, three SATA connectors and 5.1channel high definition audio output.
Home theatre boxes
Essentially a bookshelf-style case lying on its side, a miniature HTPC replicates the look of other smaller-than-rack-sized home theatre components such as a DVRDigital video recorder
A digital video recorder , sometimes referred to by the merchandising term personal video recorder , is a consumer electronics device or application software that records video in a digital format to a disk drive, USB flash drive, SD memory card or other local or networked mass storage device...
or mini audio receiver. The front panel interface is emphasized, with the optical disc drive rotated relative to the case in order to maintain horizontal mounting, and more motherboard port connectors (such as for USB) are routed to the front panel.
Computer-on-module
A Computer-on-moduleComputer-on-module
A computer-on-module or System on Module is a type of single-board computer , a subtype of an embedded computer system. An extension of the concept of System on Chip , COM lies between a full-up computer and a microcontroller in nature.- Design :Today's COM modules are complete embedded computers...
(COM) is a complete computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
built on a single circuit board. They are often used as embedded system
Embedded system
An embedded system is a computer system designed for specific control functions within a larger system. often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal...
s due to their small physical size and low power consumption. Gumstix
Gumstix
Gumstix is a company founded in 2003 by Gordon Kruberg that produces small single-board computers. The name Gumstix refers to the size of the first such computer being the approximate size of a stick of gum....
is one example of a manufacturer of COMs.