MicroATX
Encyclopedia
microATX, also known as µATX (sometimes transliterated as mATX or uATX on Internet forum
s) is a standard for motherboard
s that was introduced in December 1997. The maximum size of a microATX motherboard is 244 mm × 244 mm (9.6 in × 9.6 in), but some microATX boards can be as small as 171.45 mm × 171.45 mm (6.75 in × 6.75 in). The standard ATX
size is 25% longer, at 305 mm × 244 mm (12 in × 9.6 in).
Currently available microATX motherboards support CPU
s from VIA
, Intel
or AMD
.
microATX boards often use the same chipset
s (northbridge
s and southbridge
s) as full-size ATX boards, allowing them to use many of the same components. However, since microATX cases
are typically much smaller than ATX cases, they usually have fewer expansion slots.
Most modern ATX motherboards have five or more PCI
or PCI-Express expansion slots, while microATX boards typically have only four (four being the maximum permitted by the specification). In order to conserve expansion slots and case space, many manufacturers produce microATX motherboard with a full-range of integrated peripherals (especially integrated graphics), which may serve as the basis for small form factor
and media center
PCs. For example, the Asus
A8N-VM CSM motherboard (pictured right) features onboard GeForce 6 graphics, AC'97 audio, and gigabit Ethernet
(among others), thus freeing up the expansion slots that would have been used for a graphics card, sound card, and Ethernet card. In recent years, however, it is common even for ATX boards to integrate all these components, as much of this functionality is contained in the typical northbridge/southbridge pair. With the "must-have" functions already present on the motherboard, the need for having many expansion slots has faded, and adoption of microATX has increased even to be used in ATX cases.
A more modern limitation of a microATX case is due to its reduction in drive bays. Current southbridges support up to six SATA devices, in addition to up to four legacy IDE devices. The full range of connectors are commonly found on microATX boards, and can be fully exploited if the board is mounted in an ATX case.
In addition, some microATX cases require the use of Low-Profile PCI
cards and use power supplies with non-standard dimensions.
Internet forum
An Internet forum, or message board, is an online discussion site where people can hold conversations in the form of posted messages. They differ from chat rooms in that messages are at least temporarily archived...
s) is a standard for motherboard
Motherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...
s that was introduced in December 1997. The maximum size of a microATX motherboard is 244 mm × 244 mm (9.6 in × 9.6 in), but some microATX boards can be as small as 171.45 mm × 171.45 mm (6.75 in × 6.75 in). The standard ATX
ATX
ATX is a motherboard form factor specification developed by Intel in 1995 to improve on previous de facto standards like the AT form factor. It was the first big change in computer case, motherboard, and power supply design in many years, improving standardization and interchangeability of parts...
size is 25% longer, at 305 mm × 244 mm (12 in × 9.6 in).
Currently available microATX motherboards support CPU
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
s from VIA
VIA Technologies
VIA Technologies is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory, and is part of the Formosa Plastics Group. It is the world's largest independent manufacturer of motherboard chipsets...
, Intel
Intel Corporation
Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...
or AMD
Advanced Micro Devices
Advanced Micro Devices, Inc. or AMD is an American multinational semiconductor company based in Sunnyvale, California, that develops computer processors and related technologies for commercial and consumer markets...
.
Backward-compatibility
microATX was explicitly designed to be backward-compatible with ATX. The mounting points of microATX motherboards are a subset of those used on full-size ATX boards, and the I/O panel is identical. Thus, microATX motherboards can be used in full-size ATX cases. Furthermore, most microATX motherboards generally use the same power connectors as ATX motherboards, thus permitting the use of full-size ATX power supplies with microATX boards.microATX boards often use the same chipset
Chipset
A chipset, PC chipset, or chip set refers to a group of integrated circuits, or chips, that are designed to work together. They are usually marketed as a single product.- Computers :...
s (northbridge
Northbridge (computing)
The northbridge has historically been one of the two chips in the core logic chipset on a PC motherboard, the other being the southbridge. Increasingly these functions have migrated to the CPU chip itself, beginning with memory and graphics controllers. For Intel Sandy Bridge and AMD Fusion...
s and southbridge
Southbridge (computing)
The southbridge is one of the two chips in the core logic chipset on a personal computer motherboard, the other being the northbridge. The southbridge typically implements the slower capabilities of the motherboard in a northbridge/southbridge chipset computer architecture. In Intel chipset...
s) as full-size ATX boards, allowing them to use many of the same components. However, since microATX cases
Computer case
A computer case is the enclosure that contains most of the components of a computer...
are typically much smaller than ATX cases, they usually have fewer expansion slots.
Expandability
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...
or PCI-Express expansion slots, while microATX boards typically have only four (four being the maximum permitted by the specification). In order to conserve expansion slots and case space, many manufacturers produce microATX motherboard with a full-range of integrated peripherals (especially integrated graphics), which may serve as the basis for small form factor
Small form factor
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 litres. SFFs are available in a variety of sizes and shapes, including shoeboxes, cubes, and book-sized PCs...
and media center
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...
PCs. For example, the 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...
A8N-VM CSM motherboard (pictured right) features onboard GeForce 6 graphics, AC'97 audio, and gigabit Ethernet
Gigabit Ethernet
Gigabit Ethernet is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second , as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks where it performed...
(among others), thus freeing up the expansion slots that would have been used for a graphics card, sound card, and Ethernet card. In recent years, however, it is common even for ATX boards to integrate all these components, as much of this functionality is contained in the typical northbridge/southbridge pair. With the "must-have" functions already present on the motherboard, the need for having many expansion slots has faded, and adoption of microATX has increased even to be used in ATX cases.
A more modern limitation of a microATX case is due to its reduction in drive bays. Current southbridges support up to six SATA devices, in addition to up to four legacy IDE devices. The full range of connectors are commonly found on microATX boards, and can be fully exploited if the board is mounted in an ATX case.
In addition, some microATX cases require the use of Low-Profile PCI
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...
cards and use power supplies with non-standard dimensions.