Three form factors are AT, ATX and BTX. AT is the older Pentium, real big with just a few connectors. ATX is the most common today, mid-size, more standard connectors for future devices, the power supply is placed differently to work better and the placement of RAM is closer to the CPU which enhances performance. BTX, is designed for powerful computers so the cooling system is improved, the CPU is moved to the front of the motherboard to get cool air and has a special heat sink and an assembly on the CPU that blows air away from the CPU.
Some motherboard form factors (from smallest to largest in physical size) are: -Mini ITX -Micro ATX -ATX -E ATX
The shape and layout of a motherboard (as well as the case) is called the form factor of the motherboard/case. Different form factors include AT (old & out of date), ATX (most common), BTX(up and coming), as well as uncommon form factors like NLX.
NLX
atx,at,btx
ATX, Actually todays most common motherboard form factor used is MicroATX
The most popular form factors are: -Mini ITX -Micro ATX -ATX -E ATX
NLX BTX ATX
NLX LPX Mini LPX
NLX has slots parallel to the motherboard as ATX does not
Motherboard ka full form
Unfortuntely, the Dell motherboard form factors are propietary, so you'll have to buy replacement motherboards directly from dell.
The three factors are : Using wires of specifications that match the power requirements of motherboard . Use the fan or heat sink properly. Do not use faulty devices with mother board.