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: ''For computers form factors both larger and smaller than desktop personal computers, see list of computer size categories.'' In computing, the form factor is the specification of a motherboard – the dimensions, power supply type, location of mounting holes, number of ports on the back panel, etc. 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. Traditionally, the most significant specification is for that of the motherboard, which generally dictates the overall size of the case. Small form factors have been developed and implemented. == Overview of form factors == A PC motherboard is the main circuit board within a typical desktop computer, laptop or server. Its main functions are as follows: * To serve as a central backbone to which all other modular parts such as CPU, RAM, and hard drives can be attached as required to create a computer * To accept (on many motherboards) different components (in particular CPU and expansion cards) for the purposes of customization * To distribute power to PC components * To electronically co-ordinate and interface the operation of the components As new generations of components have been developed, the standards of motherboards have changed too; for example, with AGP being introduced, and more recently PCI Express. However, the standardized size and layout of motherboard have changed much more slowly, and are controlled by their own standards. The list of components a motherboard must include changes far more slowly than the components themselves. For example, north bridge controllers have changed many times since their introduction, with many manufacturers bringing out their own versions, but in terms of form factor standards, the requirement to allow for a north bridge has remained fairly static for many years. Although it is a slower process, form factors do evolve regularly in response to changing demands. The original PC standard (AT ("Advanced Technology" )) was superseded in 1995 by the current industry standard ATX (Advanced Technology Extended), which still dictates the size and design of the motherboard in most modern PCs. The latest update to the ATX standard was released in 2007. A divergent standard by chipset manufacturer VIA called EPIA (also known as ITX, and not to be confused with EPIC) is based upon smaller form factors and its own standards. Differences between form factors are most apparent in terms of their intended market sector, and involve variations in size, design compromises and typical features. Most modern computers have very similar requirements, so form factor differences tend to be based upon subsets and supersets of these. For example, a desktop computer may require more sockets for maximal flexibility and many optional connectors and other features on board, whereas a computer to be used in a multimedia system may need to be optimized for heat and size, with additional plug-in cards being less common. The smallest motherboards may sacrifice CPU flexibility in favor of a fixed manufacturer's choice. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「computer form factor」の詳細全文を読む スポンサード リンク
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