Motherboard form factor?

Here you go:

http://webm3308.ntx.net/motherboardforms.htm

THe differences are usually apparant, but many motherboard manufacturers are making boards that will fit both AT and ATX.

AT motherboards are usually a large square with the DIN Keyboard connector and at the back, and independant com, lpt, and PS/2 ports that can be either installed in a slot or removed from their plate and screwed into the case. The processor is usually at the front of the board.

ATX motherboards are usually rectangular with the processor situated very near the power supply at the right on the motherboard. PS/2, keybaord connectors, serial ports, USB ports, and LPT ports are usually bunched into a rectangular square that fits into a certain area of the ATX case.

Hope this helps!

Simple.......
ATX is any Pentium II 350 and above.
AT is anything like Cyrix and AMD chips.
Newer AT boards will support ATX as well.
More differences.....ATX usually has only PS2 ports for mouse and kb. ATX also does not power off straight away, hold the button for 4-5 seconds, also shutting down windows will turn the machine off completely.

Easiest way to determine board type is by power connector. On an AT form factor board the power connector will be a single row of pins with a key block to one side. On an ATX form factor board the connector is a double row and all pins fully enclosed in the connecter. MATX is simply a "Micr"ATX board. (smaller physical size than standard board). They are also generally smaller than a "Baby" ATX. Most if not all Pentium II, Celeron and Atholon based motherboards are of the ATX form factor. Main thing is to make sure that your case/power-supply will work with AT or ATX.

If the MB has a big keyboard connector it is AT. If it is a small one it is ATX. Don't listen to the idiot that say's ATX is only Pentium II 350 and above. You can get ATX for any processor type AMD, CYRIX and INTEL. Same goes for AT. You can indeed get Pentium III MB's in AT format (don't know why anyone would wan't one.

ATX is definitely the way to go all external ports are integrated into the MB. e.g. parralel, USB, serial etc. That means fewer cables to deal with inside the case.

answers 2 through --- may not be exactly right in all cases. There are some older AT mobo's that had PS2 ports instead of DIN.
Also the power button can be set up for instant off in the BIOS on the newer ATX boards, so this is not a determining factor.
Also some of the newer ATX boards have the Rectangular power plug with two rows of pins and the old AT style pins also which consists of two flat plugs with exposed pins.

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