Motherboards are basically presented in two sizes, ATX and mini ATX the ATX motherboard is 12" wide with unreliable pits whereas the mini ATX is 8.5" wide, generally with a depth that makes it nearly square.
It is power-driven from the power supply by way of a 20 or 24 pin connector the power supply is also called as SMPS.
Motherboards with microprocessors on board sell for an ATX mini with 566 MHz Celeron, and ATX with a 2.0 GHz Pentium 4 installed. There are lots of selections to choose from such as the number and type of expansions slots.
The performance of a Computer is not only determined exclusively by the MHz of processor. The performance also depends upon what type of graphics board, the speed of the memory bus you are using, the amount of memory, as well the access speed of the HDD all these thing influence Computer performance. The motherboard is the main circuit board in a PC. It contains all the circuits and components that run the PC.