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.
The analogue of size in motherboard specifications is "form factor". There are at least four major form factors in non-server architecture.
These four factors are: ATX, extended ATX, micro ATX, and mini ITX.
Of these form factors (non-server), ATX and micro ATX are by far the most prevalent.
It is an ATX motherboard. But even though it is an ATX size it is a company specific motherboard, and is not compatible with standard ATX cases.
325mm across
Motherboard manufacturers must consider capacity. They must also consider the size of the motherboard since devices are getting smaller in technology.
YES
The "form factor."
The Dell XPS 400 series uses a BTX format motherboard. A BTX motherboard measures approximately 325 by 266 milimeters.
Depending on it's size, it would likely have either an ATX or microATX motherboard.
The maximum size for a microATX motherboard is 244mm*244mm or 9.6in*9.6in.
This is a microATX (mATX) motherboard that measures 9.6 inches on a side, which is the maximum size for a mATX board. The minimum size for this style of board is 6.75 inches on a side.
The maximum size of a microATX motherboard is 244 mm × 244 mm (9.6 in × 9.6 in)
The processor size or speed does not determine how much RAM your system needs. Generally speaking, the newer the system, the more RAM you can add. The amount of RAM slots on a motherboard and the motherboard's own subsystem (the BIOS) will determine how much RAM you can add to a particular motherboard.
No. A motherboard will specify what type of memory it supports. The DIMM slot for DDR,DDR2 and DDR3 have different footprints.