Information About Computer Motherboards
The motherboard is the main component found in PC and Macintosh computers. The motherboard is what allows various hardware components to transfer information from one component to another. As computers advanced so did motherboards. The following is a listing of the various Motherboard form factors:
1. Full-AT - (12" wide x 13.8" deep) Matches the original IBM AT motherboard design, which
only fits into full size AT or tower cases only, not being produced much any more if any.
This form factor is no longer produced because it cannot be placed into the popular
2. Baby- AT - (8.57" wide x 13.04" deep) Almost the same as the original IBM XT
motherboard with modifications in the screw hole position to fit into AT style case. It has
connections built onto the motherboard to fit the holes in the case. It also has specific
placement of the keyboard and the I/O slots. This board also cannot be placed into the
3. LPX - (9.00" wide x 13.00" deep) Developed by Western Digital when making
motherboards, which was duplicated by many other manufacturers and is no longer made
by Western Digital. The LPX motherboard riser card contains all of the expansion slots.
The placement of the video, parallel, two serial and PS/2 connections have changed
4. Full-ATX - (12" wide x 9.6" deep) / Mini-ATX - (11.2" wide x 8.2" deep) The official
specifications were released by Intel in 1995 and was revised to version 2.01 in February
1997. The ATX form factor is an advancement over previous AT style motherboards.
It therefore required a new case design. ATX is not a abbreviation however is actually a
trademark which belongs to Intel. The ATX motherboard has a stacked I/O connector panel
mounted on the motherboard. On a socket 7 ATX motherboard the socket has been
placed a further distance from the expansion slots allowing for long boards to be placed in
the case easier.
a. Single keyed internal power supply connector. This is the Molex power connector, ATX
2.01. Standby voltage needs to be greater then 720 mA. The connector now cannot be
placed in improperly. While the Molex power connector allows for 5v and 3.3v to be
connected it is recommended that only a 3.3v be connected to the motherboard.
b. Relocation of the memory and the CPU creating better ventilation and easier upgrade.
c. Power management possible with proper BIOS support.
5. NLX - (Supports motherboards with overall dimensions of 9.0" x 13.6" [maximum] to 8.0" x
10.0" [minimum]) Implemented in 1998 by Intel and is similar to the LPX form factor
a. Support for the Pentium II.
b. Support for AGP.
c. Support for USB.
d. Support for DIMM memory.
e. Easier Access to internal components
f. Support for motherboards that can be removed without using tools.
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