Mainboard Form Factors

• AT Form Factor

• ATX Form Factor

• mini ATX Form Factor

• micro ATX Form Factor

• NLX Form Factor

• Form Factors, Cases & Power Supplies

The AT form factor has been on the market for a long time and enjoys large availability of cases and powersupplies and a relatively cheap price. However, this design scheme has some flaws, one of which is the inefficient cooling possibility of the CPU, which especially became apparent after the introduction of the Pentium CPU. Due to the large size which hampers the implementation of full length expansion cards, mainboards based on the Pentium II CPU are virtually impossible to be designed using this form factor.

Advantages:

• Well established standard makes for great availability and thus low price of cases, powersupplies
• Easy and relatively cheap design

Disadvantages:

• Inefficient cooling due to necessity of extra fan
• CPU socket location causes problems with full length cards
• Not suitable for Pentium II (and higher)
• I/O connections use errorprone and laborintensive cab

The ATX form factor specifications address the most pressing problems of the AT form factor and more. By more or less rotating the AT form factor`s CPU socket location 90 degrees counterclockwise, it is placed in one line with the memory modules, which increases the efficiency of the newly designed ATX powersupply`s airflow. I/O ports and multimedia connectors, which in the AT form factor were attached to the mainboard by cables and which often had to occupy the space of expansion slots, are implemented in the mainboard and have a dedicated area (double high) on the backside of the board.

Advantages:

• Efficient cooling due to powersupply design and location of CPU and DRAM
• Easy accessibility of CPU or DRAM for upgrades
• I/O connections fixed onboard prevents installation problems and shortens installation time

Disadvantages:

• Mainboard cannot be changed without first removing add-on cards and cables
• Special ATX power supply and case necessary
• Mainboard design more complex and uses more board space, which makes for higher cost
• Availability of case not as big as AT case, which makes for higher cost

Please note !

• I/O connector back panel knows many (10) layout standards, both single and double height, so make sure the ATX case descriptions of I/O connectors correspond with the mainboard`s layout
• Chaintech uses Intel layout standard
  
  

The mini ATX design has all the benefits of the ATX design and cuts cost by using a smaller PCB footprint

Advantages:

• Smaller footprint than fullsize ATX lowers cost
• Efficient cooling due to powersupply design and location of CPU and DRAM
• Easy accessibility of CPU or DRAM for upgrades
• I/O connections fixed onboard prevents installation problems and shortens installation time

Disadvantages:

• Smaller footprint allows less expansion slots
• Mainboard cannot be changed without first removing add-on cards and cables
• Special ATX power supply and case necessary
• Mainboard design more complex and uses more board space, which makes for higher cost
• Availability of case not so big as AT case, which makes for higher cost

Please note !

• I/O connector back panel knows many (10) layout standards, both single and double height, so make sure the ATX case descriptions of I/O connectors correspond with the mainboard`s layout
• Chaintech uses Intel layout standard
• Standard ATX cases and powersupplies may be used or mini ATX case (smaller).
  
  

The micro ATX design has all the benefits of the ATX design and cuts cost by using a smaller PCB footprint and opens the way to smaller and cheaper system solutions by using a micro ATX case and powersupply

Advantages:

• Smaller footprint than fullsize ATX and mini ATX lowers cost more and enables smaller system cases
• Efficient cooling due to powersupply design and location of CPU and DRAM
• Easy accessibility of CPU or DRAM for upgrades
• I/O connections fixed onboard prevents installation problems and shortens installation time

Disadvantages:

• Smaller footprint allows less expansion slots (4 in total, any of which maybe ISA, PCI or AGP)
• Mainboard cannot be changed without first removing add-on cards and cables
• Special ATX power supply and case necessary
• Availability of special micro ATX case and power supply very small

Please note !

• I/O connector back panel knows many (10) layout standards, both single and double height, so make sure the ATX case descriptions of I/O connectors correspond with the mainboard`s layout
• Chaintech uses Intel layout standard
• Standard ATX cases or mini ATX cases and powersupplies may be used or micro ATX case (smaller).
• A new powersupply is necessary for micro ATX cases (so-called SFX powersupplies)
  
  

Description:

In order to simplify PC case assembly and removal of mainboards for repair, Intel in November 1997 released the NLX specifications and made it available to the industry. In NLX the expansion slots are placed on a riser card, which makes the mainboard easy to remove: All add-in cards come with the riser card. In addition, the form factor was designed to offer a solution to build low-cost, NetPC-type devices. The specification also requires a special case as the NLX design enables add-ons and the mainboard to sit on a rail to make it easier to slide the board in and out of the system.

Advantages:

• Easy access to mainboard shortens installation or upgrade time
• Center of design is risercard instead of mainboard, so cables to devices don`t have to be removed when mainboard is replaced
• Ready for future generations of processors
• Scalable solution from small footprint NetPC type devices until server systems
• OEM`s can stock cases with risercards with multimedia functions and stock less mainboards for last minute mainboard installation possibility (fast time-to-market)

Disadvantages:

• Special NLX power supply and case necessary
• Availability of case and power supply very small at this moment (chicken-and-egg problem between market acceptance and availability)

Please note !

• Risercard is shipped with mainboard, which causes higher price compared to current mainboards