Motherboard Form Factors

Updated on February 7, 2019
Patkay profile image

Patrick, a computer technician, is a dedicated writer who wishes to make the world better by informing individuals who seek more knowledge.

Types of Motherboard Form Factors

The motherboard form factor describes its general shape, the type of case and power supply it can use, and its physical organization (layout of the motherboard). Over time, in the computer industry, we have had a number of different motherboard form factors being developed.

AT and Baby AT (Advanced Technology)

In the early days of the computer, the AT and baby AT form factors were the most common motherboard form factors. These two variants differ primarily in width: the older full AT board is 12" wide. It is an obsolete motherboard form factor only found in older machines, 386 class or earlier.

One of the major problems with the width of this board (aside from limiting its use in smaller cases) is that a good percentage of the board "overlaps" with the drive bays. This makes installation, troubleshooting and upgrading more difficult.

A Baby AT motherboard is 8.5" wide and 13" long. The reduced width means much less overlap in most cases with the drive bays, although there usually is still some overlap at the front of the case.

Baby AT motherboards are distinguished by their shape, and usually by the presence of a single, full-sized keyboard connector soldered onto the board. The serial and parallel port connectors are almost always attached using cables (ribbons) that go between the physical connectors mounted on the case, and pin "headers" located on the motherboard. Most of the boards use AT power supplies and the system units tend to be tower casing.

AT Motherboard

AT motherboard. Note: at the top right hand corner of the board, we have the AT keyboard port
AT motherboard. Note: at the top right hand corner of the board, we have the AT keyboard port | Source

Advantages of the Baby AT Motherboard Design

  1. The size of 8.5” by 10” makes it easier to design smaller desktop PCs
  2. Most of the board is easily accessible for upgrades and expansion

Disadvantages of the Baby AT design

  1. CPU location- with the processor and heat sink in place, it is difficult to fit a long expansion card into one of the expansion slots. This is the main problem encountered with the AT-style motherboard-the CPU can get in the way of the expansion cards.
  2. Motherboard mounting - some system cases are not drilled or punched to support all the mounting holes on a Baby AT motherboard. Therefore, the front edge of the system board tends to be left unsupported and over time this edge can warp (bend) leading to loose components and expansion cards causing intermittent problems.

ATX and Mini ATX Motherboard Form Factors

Full-ATX – (12" wide x 9.6" deep) / Mini-ATX – (11.2" wide x 8.2" deep).

The ATX, Created by Intel in 1995, was developed as an evolution of the Baby AT form factor and was defined to address four areas of improvement:-

  • Enhanced ease of use
  • Better support for current and future I/O
  • Better support for current and future processor technology, and
  • Reduced total system cost.

The ATX is basically a Baby AT rotated 90 degrees and providing a new mounting configuration for the power supply. The processor is relocated away from the expansion slots, (unlike Baby AT) allowing them to hold full-length add-in cards.

The longer side of the board is used to host more onboard I/O ports. The ATX power supply, rather than blowing air out of the chassis, as in most Baby AT platforms, provides air-flow through the chassis and across the processor.

ATX Motherboard


Some Improvements of the ATX Motherboard Form Factor

  • Integrated I/O Port Connectors: Baby AT motherboards use headers which stick up from the board, and a cable that goes from them to the physical serial and parallel port connectors mounted on to the case. The ATX has these connectors soldered directly onto the motherboard.
  • Integrated PS/2 Mouse Connector: ATX motherboards have the PS/2 port built into the motherboard.
  • Reduced Drive Bay Interference: Since the board is essentially "rotated" 90 degrees from the baby AT style, there is much less "overlap" between where the board is and where the drives are thus making it easy to access the board, and fewer cooling problems.
  • Reduced Expansion Card Interference: The processor socket/slot and memory sockets are moved from the front of the board to the back right side, near the power supply. This eliminates the clearance problem with baby AT style motherboards and allows full-length cards to be used in most (if not all) of the system bus slots.
  • Better Power Supply Connector: The ATX motherboard uses a single 20-pin connector instead of the confusing pair of near-identical 6-pin connectors on the baby AT form factor.
  • "Soft Power" Support: The ATX power supply is turned on and off using signaling from the motherboard, not a physical toggle switch. This allows the PC to be turned on and off under software control, allowing much-improved power management.
  • 3.3V Power Support: The ATX style motherboard has support for 3.3V power from the ATX power supply.
  • Improved Design for Upgradability: In part, because it is the newest design, the ATX is the choice "for the future". More than that, its design makes upgrading easier because of more efficient access to the components on the motherboard.

MicroATX Motherboard Form Factor

This form factor was developed as a natural evolution of the ATX form factor to address new market trends and PC technologies. MicroATX supports:

  • Current processor technologies
  • The transition to newer processor technologies
  • AGP high-performance graphics solutions
  • Smaller motherboard size
  • Smaller power supply form factor

Flex ATX

This is a subset of MicroATX developed by Intel in 1999. It allows more flexible motherboard design, component positioning, and shape. Can be smaller than regular microATX.

  • Supports current socketed processor technologies
  • Smaller motherboard size
  • ATX 2.03 I/O panel
  • Same mounting holes as microATX
  • Socket only processors to keep the size small

LPX and Mini LPX (Low Profile Casing eXtended)

Note: These Motherboard Form Factors are obsolete.

The LPX motherboard form factors are designed to be used in small Slimline or "low profile" cases typically found on low profile desktop systems. The primary design goal behind the LPX form factor is reducing space usage (and cost).

The most distinguishing feature is the riser card that is used to hold expansion slots. The riser card of the LPX motherboard form factor is situated at the center of the motherboard. Expansion cards plug into the riser card; usually, a maximum of just three. This means that the expansion cards are parallel to the plane of the motherboard.

This allows the height of the case to be greatly reduced since the height of the expansion cards is the main reason full-sized desktop cases are as tall as they are. The problem is that you are limited to only two or three expansion slots!

While the LPX form factor can be used by a manufacturer to save money and space in the construction of a custom product, these systems suffer from non-standardization, poor expandability, poor upgradability, poor cooling and difficulty of use for the do-it-yourself.

LPX Motherboard Form Factor

LPX Motherboard with a riser card mounted.
LPX Motherboard with a riser card mounted. | Source
The riser card, where adapter cards are connected
The riser card, where adapter cards are connected

NLX (New Low Profile eXtended) Form Factor

Note: This motherboard form factor is also obsolete.

The need for a modern, small motherboard standard led to the development of the new NLX form factor. In many ways, NLX is similar to LPX. Also like ATX, the NLX standard was developed by Intel Corporation in 1998.

NLX still uses the same general design as LPX, with a smaller motherboard and a riser card for expansion cards. The riser card is pushed to one extreme edge of the motherboard.

NLX makes the following main changes:-

  • Revised design to support larger memory modules and modern DIMM memory packaging.
  • Support for the newest processor technologies, including the new Pentium II using SEC packaging.
  • Support for AGP video cards.
  • Better thermal characteristics, to support modern CPUs that run hotter than old ones.
  • More optimal location of CPU on the board to allow easier access and better cooling.
  • More flexibility in how the motherboard can be set up and configured.
  • Enhanced design features, such as the ability to mount the motherboard so it can slide in or out of the system case easily.
  • Support for desktop and tower cases.

NLX Motherboard Form Factor

An Illustration of NLX Motherboard Form Factor
An Illustration of NLX Motherboard Form Factor | Source

Was this article helpful

See results

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2011 Patrick Kamau


    0 of 8192 characters used
    Post Comment
    • profile image


      4 months ago


    • profile image


      5 months ago

      Very helpful..thanks alot sir.

      God bless you

    • Patkay profile imageAUTHOR

      Patrick Kamau 

      8 years ago from Nairobi, Kenya

      Thanks Delight, F P I, I am glad that benefited by reading this hub.

    • profile image

      Delight, F P I 

      8 years ago

      This really help me in my school programmes in computer hardware. Thanks

    • profile image

      Delight, F P I 

      8 years ago

      This really help me in my school programmes in computer hardware. Thanks

    • Patkay profile imageAUTHOR

      Patrick Kamau 

      8 years ago from Nairobi, Kenya

      You need to check whether the problem is within the atx 4 cables or the display system. If the problem persists you can have it checked by a technician.

    • profile image


      8 years ago

      i have foxconn g31 mpx series

      there is problem

      when i connect atx 4 cables for processor my motherboard is not working when i turn of this cable than my motherboard work but no display

      how can i solve this problem

      plz help me

    • Patkay profile imageAUTHOR

      Patrick Kamau 

      8 years ago from Nairobi, Kenya

      Thanks Prince Rich J.ICT has really changed the world, making things easier for us.

    • profile image

      Prince Rich J. 

      8 years ago

      I thanks secientices by bringin ICT in d world 2day, especially Nnamdi Azikiwe University. Awka

    • Patkay profile imageAUTHOR

      Patrick Kamau 

      8 years ago from Nairobi, Kenya

      Thanks ANDREW AMATETE, my wish is to inform people and make them more aware about the computer they use daily.

    • profile image


      8 years ago



    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)