A CPU's pins supply power and facilitate data transfer.
Upgrading a computer's CPU can be a confusing process for those without technical training because it's never safe to assume that your computer's motherboard is compatible with the CPU you want to use. A motherboard is designed with a specific series of CPUs in mind, and you can generally upgrade your current CPU only with another one from the same series. Motherboards have several physical and design aspects that limit the CPUs you can install.
CPU Socket
A motherboard's CPU socket physically limits the types of processors that you can install. Because each type of CPU socket has a specific number of pin holes, it's physically impossible to install an incompatible processor without damaging the pins on the bottom. Some motherboards have slots instead of sockets for the installation of card-based CPUs such as the Intel Pentium II and Pentium III. Because Intel transitioned from slot-based to socket-based Pentium III processors, it may be possible to install a socket-based CPU in some CPU slots using an adapter called a "Slotket."
Motherboard Chipset
A motherboard's chipset consists of two small microprocessors -- the northbridge and southbridge -- that act as traffic controllers and direct the flow of data between the computer's processor, memory and components. If the CPU is the computer's brain, you can think of the chipset as a separate brain for the motherboard. A chipset must be compatible with a particular CPU for it to work with the motherboard.
Bus Speed
A CPU achieves its clock rate by multiplying the motherboard's bus speed -- the speed at which it transfers data between components -- by a fixed number. For example, a CPU with a multiplier of 7.5 designed to operate at a bus speed of 133 MHz has a clock rate of 997.5 MHz. Although the CPU may work on a motherboard with a maximum bus speed of 100 MHz, it would operate at a clock frequency of 750 MHz and couldn't reach its top speed.
Core Voltage
A motherboard must supply power to a CPU for it to operate. The amount of power that a CPU requires is its core voltage. In some cases, a manufacturer may release a new version of a processor that requires a higher core voltage than the previous version. This can cause the new processor to be incompatible with existing motherboards, even when those motherboards have the same socket type. This happened in 2001 with a release of Intel's final Pentium III model. This version -- codenamed Tualatin -- required a core voltage of 1.45 or 1.475 volts, while the previous Coppermine Pentium III required 1.75 volts. In addition to problems with older motherboard chipsets, this caused the Tualatin to be incompatible with existing motherboards.
Tags: clock rate, compatible with, core voltage, data between, existing motherboards