What is Data Communication Equipment (DCE)
ATX (Advanced Technology Extended) is a combination of standards for computer system power supplies and chassis dimensions. It was developed as a replacement for the once-common AT form factor.
Baby ATx and ATx
The closest thing that standardizes size and shape is what's known as a "Form Factor". Common form factors are AT, ATX, BTX and ITX. The most common is ATX. These form factors specify motherboard sizes and general component placement. For example, you usually need an ATX compatible computer case if you wish to fit it with an ATX motherboard.
The three form factors for desktop system boards are: ATX, and BTX and NLX
A full ATX offers more flexibility than a Micro ATX or a Mini ATX.
The ARP590 supports of ATX and Extended ATX motherboards means dual processor solutions for your mobile coputing needs. The ARP590 series portable platform provides a totally integrated solution for mobile computing applications requiring industrial ruggedness, robustness and system configurations found in desktop workstations. The chassis supports Micro-ATX, ATX, and Extended ATX form factor motherboards. This means the latest motherboard designed for desktop PC, workstation, or server are available to you to customize it with your processor and peripheral options.
All motherboards will work fine, save server one. Consider getting a standard ATX or micro-ATX motherboard.
ATX Computer Cases
Two common types of motherboard are ATX and Micro-ATX. An ATX motherboard is much larger and allows for additional hardware to be installed.
There's actually three: ATX, Mini ATX, and Micro ATX. The difference is only in size. Mini is about half the size, Micro is 1/3 But of course with the size, you sacrifice extra ports, usually PCI expansion ports.
It depends on the type of board you have. Obviously a laptop mobo (motherboard) is going to be smaller than one in a desktop. And again a desktop one is going to be different than one for a server. Motherboards are categorised by a thing called form factor. So for example the form factor of an ATX board is going to be different than the form factor of an extended ATX. ATX would be the standard board you would use in a desktop PC. Whereas you might use mini-ATX for one of those new mini computers you see, or you might use extended-ATX in a server. So when someone asks what form factor the board is, they're really just asking "is it atx or micro-atx or mini-atx etc..." And obviously each form factor is going to be different in size. There are some very good online tutorials about mobo's, check google.
Full AT, Baby AT, and ATX