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MotherBoard Form Factors

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Current MotherBoard form factors; Also sub-divided into the Processor Socket types:
Socket refers to the type of processor ZIF socket used. Slot refers to the Processor residing in a Daughter card.

...AT: 12" x 11" - 13" [Obsolete, replaced by the Baby-AT, and ATX form factors]
...Baby AT: 11.2" wide x 8.2" deep. Original IBM PC Motherboard
...microATX: 9.6" wide x 9.6" deep (244mm x 200mm).
...Mini-ATX: 11.2" wide x 8.2" deep. Smaller version of the ATX Mother Board.
...Flex ATX:9.0" wide x 7.5" deep (229mm x 190.5mm). Differs from microATX; new socketed processor, smaller, ATX 2.03 I/O panel
...NLX: (9.0" wide x 13.6" deep) to (8.0" wide x 10.0" deep) and any size in between.
...LPX: 9" x 11" - 13" [228.6mm x 279.4 - 330.2 mm]. Expansion slots are mounted on a bus riser that connects to the motherboard.
........MiniLPX: 8" - 9" x 10" - 11" [203 - 228mm x 254 - 279mm]. Smaller version of the LPX Motherboard
...WTX: (workstations)
...ATX: 12" wide x 9.6" deep (305mm x 244mm). Essentially a Baby AT mother board rotated 90 degrees in the chassis. Released 1996.
........Slot 1: [242 pins] Intel Pentium II/III. AMD Celeron
........Slot 2: Dual Xeon
........Slot A: AMD Athlon, Thunderbird, Duron K7;
........Socket A: AMD Duron, Sempron, Thunderbird and XP Athlon microprocessors [Socket A graphic]
........Socket T: Intel Pentium 4, 775 conductor Prescott CPU
........Socket 1: [169 pins] Intel 486SX, 486DX, 486DX2, 486DX4 processors
........Socket 2: [238 pins] Intel 486SX, 486DX, 486DX2, 486DX4, Pentium processors
........Socket 3: [237 pins] Intel 486SX, 486DX, 486DX2, 486DX4, Pentium. AMD, Cyrix processors
........Socket 4: [237 pins] Intel Pentium 1 66MHz
........Socket 5: [320 pins] Intel Pentium 75MHz, 133MHz
........Socket 6: [235 pins] Intel 486DX, Pentium
........Socket 7: [321 pins] Intel Pentium. AMD K6-2, K6-III; (Super 7): TBD
........Socket 8: [387 pins] Intel Pentium Pro [Socket 8 graphic]
........Socket 370: Pentium II/III, Celeron [Socket 370 graphic]
........Socket 393: AMD Athlon
........Socket 423: Intel Pentium 4
........Socket 462: AMD
........Socket 478: Intel Pentium 4, smaller than Socket 423
........Socket 603: Intel Pentium 4, Intel Xeon processor
........Socket 604: Intel Pentium 4, Intel Xeon processor
........Socket 754: AMD Sempron, Athlon; 64-bit, 'single-channel' memory-controller and use unbuffered (non-registered) memory
........Socket 775: Intel Pentium 4
........Socket 939: Athlon 64 and Athlon 64 FX processors [128-bit, 'dual-channel' memory-controller]
........Socket 940: AMD Athlon 64 FX, Opteron processors [Server/Workstation, require registered memory]
........Socket AM2: AMD Athlon 64 Dual Core processors supporting DDR2 memory [M2 was the old name]
........Socket AM3: AMD Phenom II processors supporting DDR3 memory. AM3 uses 941 pins in a ZIF socket.
........Socket F: [FM1, FM2, FM3] AMD X2 Opteron processors [2xx 8xx server processors]
........Socket FM1, FM2, FM3: AMD processors
........Socket G3: [G3MX] AMD X2 processors [Supporting the DDR3 memory specification from JEDEC1]
...Extended ATX: 12" x 13.05" (W x H), also called EATX
...EmbATX: (EmbeddedATX) Same size as microATX, w/ height of 2 inches
...FlexATX: 228.60mm x 2190.50mm (Width x Depth)
...microATX: 243.84mm x 243.84mm (Width x Depth)
...BTX: (Balanced Technology Extended) 325.12mm wide x 266.70mm deep [7 Expansion Slots]
........microBTX: (Balanced Technology Extended) 264.16mm wide x 266.70mm deep [4 Expansion Slot]
........nanoBTX: (Balanced Technology Extended) 223.52mm wide x 266.70mm deep [2 Expansion Slot]
........picoBTX: (Balanced Technology Extended) 203.20mm wide x 266.70mm deep [1 Expansion Slot]
...ITX: 220mm x 170mm
........mini-ITX: 170mm x 170mm
........nano-ITX: 120mm x 120mm
........pico-ITX: 72mm x 100mm
...DTX: (Acronym not defined) 244mm wide x 200mm deep [2 Expansion Slots]
........miniDTX: (Acronym not defined) 170 wide x 200mm deep [2 Expansion Slot]

Server Formats. Server System Infrastructure (SSI) Specifications.
........CEB; (Compact Electronics Bay) 305mm x 267mm. Server, dual or multi processor motherboards.
........EEB; (Enterprise Electronics Bay) 305mm x 330mm. Server, dual or multi processor motherboards.
........TEB; (Thin Electronics Bay) 411mm x 330mm. Server, dual or multi processor motherboards.

Embedded Mother Board Formats:
........EBX; 8.00" x 5.75"
........ECX; 105mm x 146mm. Embedded Compact Extended Form Factor [Small Form Factor]
........ePCI-X; 8.00" x 5.75". Embedded PCI eXtended
........ETX; (Embedded Technology eXtended) 95mm x 111.6mm (5.75 x 8 inches)
........ETXexpress; (Embedded Technology eXtended) 90mm x 125mm, based on the PCIexpress bus
........EPIC; (Embedded Platform for Industrial Computing) 4.528" x 6.496" (115mm x 165mm). Contains a PC/104 stack area
........SOM-ETX; (System On Module - ETX) 4.50" x 3.70" (114mm x 95mm)
........5.25" Mini Module; 8.0" x 5.75" (203mm x 146mm)
Embedded Cards by Board Form Factor
There are also a number of PC power supply standards which appear as Mother Board specifications:
..ATX12V: ATX power supply specification
..CFX12V: [Compact Form Factor] power supply specification
..LFX12V: [Low Form Factor] another variation of the BTX12V power supply specification
..SFX12V: microATX and FlexATX power supply specification
..TFX12V: [Thin Form Factor] for small and low profile microATX and FlexATX system layouts

Embedded Mother Board manufacturers are listed on the OEM COTS MotherBoard Manufacturers page.
Memory Module formats and manufacturers are listed on the Memory Module Formats and Manufacturers page.
New form factors are developed all the time, this list may not cover all of them.

This is a listing of Personal Computer Mother Board form factors.
The approximate size of the board is listed after the common name.
In many cases the the style of processor is also listed. Computer Buses

{MotherBoard Size Index}

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