Small form factor

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A small form factor is a computer form factor designed to minimize spatial volume, typically measured in liters. Generally, the phrase "small form factor" applies to desktop computers and not to computing systems that have traditionally been small, such as embedded or mobile systems.[1] However, "small form factor" lacks a normative definition and is consequently misappropriated as a buzzword due to its growing popularity. Manufacturers often provide self-serving definitions.[2]

The size of SFF PCs vary widely, from 1 L to 30 L or more, but as of 2007 the volume of a shoe box is typical. Their shapes vary from cubes to mini-towers to shallow flat cases resembling home theater components (such as VCRs or AV receivers).

Motherboard form factor comparison


[edit] Uses

Because they are built around small motherboards, SFF computers can be far smaller than typical desktop computers. They are often used in space-limited areas where normal computers cannot be placed. SFF computers have also found a niche as home theater PCs, as well as for mobile applications such as LAN parties. Many users simply enjoy the aesthetic and ergonomic benefits of a small system which, unlike a full-size tower case, can easily fit on top of a small desk.

Some SFF computers go further, employing more compact components designed for portable computers, 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.

[edit] Features

Small form factor computers are generally designed to support the same features as modern desktop computers, but in a smaller space. Most accept standard x86 microprocessors, standard DIMM memory modules, standard 3.5 inch hard disks, 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 don't always fit inside an SFF computer, so some manufacturers provide custom cooling systems. Many SFF cases only have room for one to four expansion cards, although very few have the space for larger cards— such as the GeForce 8800GTX—. Many SFF computers use highly integrated motherboards containing many on-board peripherals so that expansion cards are not needed; many of these motherboards use custom form factors, while others use the microATX standard.

Some "box type" SFF cases (recently very popular) can fit standard ATX power supplies, while others require custom power supplies or external power bricks.

[edit] SFF Types

There are many different types of SFF computers[3] available as of 2008. They may be categorized loosely by their overall shape and size.

[edit] Cubical

Shoebox case

Many SFF computers have a cubical or nearly cubical shape. Smaller models are typically sold as barebones units, including a case, motherboard, and power supply designed to fit together. The motherboard lays 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.

Larger cases, called box type, tend to have a shoe box structure to them. They take microATX motherboards which, again, lay flat on the base of the case. They are normally sold as bare cases which can be easily upgraded thanks to the standard motherboard form factor and greater internal space. The Antec NSK1300, APEVIA X-QPack, PC Design Lab's Qmicra, Silverstone SG01 (SG01 Review) and Ultra Micro Flyare common examples of box-type SFF computers.

[edit] Mini computers

Apple's Mac Mini is similar in size to a Mini-ITX based PC.

Until recently, SFF cases were usually sold alone, or as barebones units (case, power supply, and motherboard). They were marketed primarily to enthusiasts who wanted to build their own custom computers. In 2005, Apple Inc. introduced its Mac Mini (volume of 1.4 L, excluding external power brick). As of 2006, 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. As of 2007, several other companies have released similar computers that focus on small size, low price, and extremely high power efficiency (typically 10 W or below in use). Zonbu, fit-PC, Linutop, and A9Home are examples of these.

The HP Slimline uses a non-standard motherboard that is very similar in size to Mini-ITX.[4]

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 and incorporate 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 (7x10x2" vs 6.5x6.5x2"), and barely bigger than a standard 5.25" optical drive.

[edit] Mini-towers

Mini-towers are comparable in height to a monitor

A mini-tower is designed to optimally fit microATX and its contemporaries. It resembles an ATX mid-tower case but is shorter in height, and sometimes depth. Height can be further reduced by having the power supply mounted sideways, just above the expansion slots, rather than in the usual position above the motherboard. Mini-towers can fit ATX power supplies, or alternatively save additional space by specifying SFX or TFX power supplies. The primary design goal of microATX was not to reduce size, but to reduce costs while maintaining features similar to ATX. Because of this, the profile of a typical mini-tower is not drastically different from that of a mid-tower, and they are generally considered to be an intermediate size rather than a true SFF.

[edit] Home theater boxes

HTPC configuration

Essentially a mini-tower laying on its side, an HTPC case replicates the look of other home theater components such as a DVR or amp. 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.

[edit] See also

[edit] References

  1. ^ Joe Rybicki (May 2007). "The Incredible Shrinking Game Machine! Part One: The Small Form-Factor PC". Games for Windows: The Official Magazine (6): 92–96. "Yes, early small form-factor machines (let's just call 'em SFFs) had some issues. OK, a lot of issues. Designed for the gimpiest casual user, these mini-PCs didn't offer many options in the way of upgrades or power. The cases were often too small to fit a full-size videocard [...] Still, two very specific users saw the SFFs' potential. First, home theater enthusiasts realized that these pint-sized PCs made for ideal media center hubs, and second, LAN partygoers naturally glommed on to them for the portability factor. [...] we could see the SFF market gaining a lot more momentum. Until then, enjoy being the first on your block to squeeze a full-size tower's worth of top-level gear into a shoebox-size package.". 
  2. ^
  3. ^ "List of Small Form Factors," PC/104 and Small Form Factors, 2008
  4. ^ HP and Compaq Desktop PCs - Motherboard Specifications, PTGV-DM (Onyx2)

[edit] External links

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