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Epox EP-8KHA+ with Socket 462 Mainboard

The term form factor refers to the type, design, or style of a particular case. This page will describe the various form factors that case units are designed with.

The term form factor refers to the architecture of a particular case. The form factor of a motherboard determines the type of case required for a proper system build. There are generally three types fo form factors available to end users. This page will describe all three.

How To Migrate To A New Case Design
This document will outline concepts associated with migrating to a new case type. In this article, I provide a case by case comparison between a variety of units to help you make a smarter, more economical buying decision when upgrade time comes
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Introduction Case Architecture Case Form Factors How It Connects
Introduction And Overview Of Case Form Factors
Mid Tower Cases

ATX Mid Tower - The ATX Mid tower case is the most common type of case to be used in desktop workstations at present day. ATX mid tower cases offer more room for expansion and are cheaper to implement.

ATX Full Tower - The ATX Full tower is in the same family of the ATX mid tower case, but generally adds more expansion bays and supports server motherboards in addition to regular desktop motherboards

Small Form Factor

Small Form Factor - The Small Form Factor case is much smaller than the Micro ATX case and generally suited for computers that serve as a multimedia PC or for playing back multimedia such as DVD movies or MP3 music.

Types Of Small Form Factor Cases


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.

Flat or Pizza Box

These are low, flat cases resembling the pizza box form factor which was formerly very popular for computer workstations. They usually fit microATX motherboards which lay flat on the base or side of the case (depending on how it is oriented in use). The NeXT NeXTStation from the early 1990s is a good example of this case design.

Many cases designed for home theater purposes are based on this design (though others are too large to be considered SFF). They feature front-panel controls, ports, and styling designed to reproduce the look and convenience of traditional home theater components such as VCRs and DVD players. The NMEDIAPC HTPC 180 is an example of this design.

Lunch Box

A Lunchbox case is a narrow, high-profile enclosure designed to sit horizontally and support a monitor. They usually have fewer expansion slots than full desktop cases but are otherwise similar. Some past computers in lunch box cases include the Apple Macintosh IIci, the SPARCstation ZX and ACME, EMP370. Roughly equivalent to a minitower on its side, this design is seldom used for new hardware, for similar reasons as Pizza boxes.


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 t


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 notebook 5.25" optical drive.

Micro ATX

The mini atx unit also known as a shuttle PC, best suited for entertainment based computers.

It is important to note that an ATX motherboard will not mount into a Micro ATX case. However, a Micro ATX motherboard will fit properly in an ATX Mid Tower or ATX Full Tower case.

  • Micro ATX Case - A micro ATX case implements a very small design. They take up less space but are very hard to maneouver when building a computer due to their very small insides.

microATX towers resemble normal tower cases but are shorter in height, and sometimes depth. They are designed to fit microATX motherboards, but not larger ATX motherboards. They may use standard ATX power supplies, or may come with proprietary PSUs. The Antec NSK3300 (volume of nearly 25 L) and Silverstone SG03 (volume around 22 L) are examples of microATX tower cases. Because they are very similar to full-size tower cases, microATX tower cases are not always recognized as small form factor cases.


Small Form Factor

Micro ATX Form Factor

microATX is a motherboard form factor Intel introduced in December 1997 as an evolution of the
ATX form factor for smaller and lower-cost systems. The reduced size compared to standard ATX
allows for a smaller chassis, motherboard, and power supply, thereby reducing the cost of the entire system. The microATX form factor is also backward-compatible with the ATX form factor and can be
used in full-size ATX cases. Of course, a microATX case doesn’t take a full-size ATX board. This form
factor has become popular in the low-cost PC market. Currently, mini-tower chassis systems dominate
the low-cost PC market, although their small sizes and cramped interiors severely limit future

ATX Form Factor
The ATX form factor was the first of a dramatic evolution in motherboard form factors. ATX is a combination of the best features of the Baby-AT and LPX motherboard designs, with many new enhancements and features thrown in. The ATX form factor is essentially a Baby-AT motherboard turned sideways in the chassis, along with a modified power supply location and connector. The most important thing to know initially about the ATX form factor is that it is physically incompatible with either the previous Baby-AT or the LPX design. In other words, a different case and power supply are required to match the ATX motherboard. These case and power supply designs have become common and are found in most new systems.
Thin Clients

A thin client (sometimes also called a lean or slim client) is a client computer or client software in client-server architecture networks which depends primarily on the central server for processing activities, and mainly focuses on conveying input and output between the user and the remote server. In contrast, a thick or fat client does as much processing as possible and passes only data for communications and storage to the server.

Many thin client devices run only web browsers or remote desktop software, meaning that all significant processing occurs on the server. However, recent devices marketed as thin clients can run complete operating systems such as Debian Linux, qualifying them as diskless nodes or hybrid clients. Some thin clients are also called "access terminals."

As a consequence, the term "thin client", in terms of hardware, has come to encompass any device marketed as, or used as, a thin client in the original definition – even if its actual capabilities are much greater. The term is also sometimes used in an even broader sense which includes diskless nodes.

History Of Thin Clients

What are now called thin clients were originally called "graphical terminals" when they first appeared, because they were a natural development of the text terminals that had gone before them. (Text terminals are essentially the ultimate thin client, but are generally not classified as such because they come from an earlier computing era.)

X terminals were a relatively popular form of graphical terminal in the 1990s.

Late in the Windows NT 3.51 life cycle, Citrix Systems approached Microsoft with an idea for a multi-user version of Windows similar to what had been done with Unix. Microsoft agreed to license the Windows NT 3.51 source code which Citrix then turned into a product called WinFrame; a version of NT 3.51 that allowed multiple users to run on the same server. Microsoft later licensed the technology back from Citrix and incorporated it into a special version of NT 4.0 (known as NT 4.0 TSE, or Terminal Server Edition) and then into all subsequent version of their server operating systems. The code name for this Microsoft project was Hydra.

Terminal Services allows the operation of standard Windows software in a mainframe model centralized computing vs. distributed computing. Users log onto the server using thin client hardware and the server creates a session in memory dedicated to that user. Any GUI commands that would normally be sent to a local graphics card are instead compressed and sent to the client. Likewise, user keyboard and mouse movements are sent back to the user's task running on the server.

It is likely that the term "thin client" started to be used instead of "graphical terminal" for the following reasons:

  • When thin clients started to come back into vogue, fat clients had long been the norm in most environments. Many IT workers and managers used to working with fat clients such as PCs and Macs would have been unfamiliar with the term "graphical terminal".
  • The term "thin client" is more descriptive and relevant than "graphical terminal", in an age in which all desktop computing devices have graphical capabilities.
  • As a marketing term, it sounds short and snappy[citations needed] – and also, importantly, it made the technology sound innovative and technologically advanced, even though it was neither – X terminals had been acting as thin clients years before the term was widely used in the IT industry.
  • "Thin Client" also reflects the fact that most of these devices leave out much of the hardware found in typical PCs, such as hard drive, cooling fan and much of the RAM.


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