Processors each fit into a socket on the center-top area of the motherboard. The socket allows them to communicate with the rest of a computer's components. Your motherboard's socket must match the processor's socket number exactly in order for your processor to work correctly. Placing an LGA775 socket processor into an LGA1366 socket motherboard won't work, for example, and causes damage to both the processor and the motherboard. The processor's socket number appears on the top of your processor and near the socket on the motherboard.
Turn your computer around and disconnect all the cables from the rear panel.
Remove the two or three screws holding the right cover to the right side of the computer's chassis.
Lift off the cover and lay the computer on its side so that the exposed interior faces up to you.
Unclip your processor's cooling fan and lift it off.
Take a dry cloth and clean the surface of your processor of all the paste on it until letters and numbers start appearing on the surface. Look for a code starting with "LGA," "Socket," "Sct," or "S." This code represents your processor's socket number. Look below the socket on the motherboard. The closest number to the socket represents the motherboard's socket number.