Wednesday, October 10, 2012

What is PC Motherboard

The Motherboard is the most important component in a PC system. Virtually every internal component in a PC connects to the motherboard, and its features largely determine what your computer is capable of, not to mention its overall performance. Although I prefer the term motherboard, other terms such as main board, system board, and planar are interchangeable. This chapter examines the various types of motherboards available and those components typically contained on the motherboard and motherboard interface connectors.

Several common form factors are used for PC motherboards. The form factor refers to the physical dimensions (size and shape) as well as certain connector, screw hole, and other positions that dictate into which type of case the board will fit. Some are true standards (meaning that all boards with that form factor are interchangeable), whereas others are not standardized enough to allow for interchangeability. Unfortunately, these nonstandard form factors preclude any easy upgrade or inexpensive replacement, which generally means they should be avoided. The more commonly known PC motherboard form factors include the following:

Obsolete Form Factors
■ Baby-AT (PC and XT)
■ Full-size AT
■ LPX (semiproprietary)
■ BTX, microBTX, picoBTX

Modern Form Factors
■ ATX and variants; microATX, FlexATX, DTX/Mini-DTX, and ITX/Mini-ITX

PC motherboard form factors have evolved over the years from the Baby-AT form factor boards based on the original IBM PC and XT, to the current ATX form factor (and variants) used in most desktop and tower systems. ATX has a growing number of variants, mostly in smaller sizes designed to fit different market segments and applications. The short-lived BTX form factors relocated major components to improve system cooling and incorporate a thermal module.

Anything that does not fit into one of the industry-standard form factors should be considered proprietary. Unless there are special circumstances, I do not recommend purchasing systems based on proprietary board designs because they are difficult to upgrade and expensive to repair because components such as the motherboard, case, and power supply are not interchangeable with other systems. I often call proprietary form factor systems “disposable” PCs because that’s what you must normally do with them when they are too slow or need repair out of warranty.

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