On large machines, CPUs require one or more printed circuit boards. On personal computers and small workstations, the CPU is housed in a single chip called a microprocessor. Since the 1970's the microprocessor class of CPUs has almost completely overtaken all other CPU implementations.

The CPU itself is an internal component of the computer. Modern CPUs are small and square and contain multiple metallic connectors or pins on the underside. The CPU is inserted directly into a CPU socket, pin side down, on the motherboard. Each motherboard will support only a specific type or range of CPU so you must check the motherboard manufacturer's specifications before attempting to replace or upgrade a CPU. Modern CPUs also have an attached heat sink and small fan that go directly on top of the CPU to help dissipate heat.

Two typical components of a CPU are the following:

• The arithmetic logic unit (ALU), which performs arithmetic and logical operations.
• The control unit (CU), which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.

See "What Is CPU Overclocking?" in the "Did You Know...?" section of Webopedia.
Also see All About Dual-Core Processors  in the "Did You Know...?" section of Webopedia.
To understand how your computer system communicates with your CPU, see "Understanding PC Buses" in the Did You Know...?" section of Webopedia.

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PC system processor reference guide 
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Webopedia: What Is CPU Overclocking?
Basically overclocking means to run a microprocessor faster than the clock speed for which it has been tested and approved.

Webopedia's "Did You Know... AMD & Intel Processor Lineups"
It never fails. Just after you upgrade your CPU, Intel or AMD announces a new processor, pushing technology to new limits — at least its next processor.

Webopedia's "Did You Know...?" Section
Use this Webopedia knowledge section for an in-depth overview of specific technologies and occurrences in the areas of Computer Science, The Internet, and Computer Hardware and Software.

Webopedia's Quick Reference Section
Use this Webopedia reference section for information on common Internet and computer facts and occurrences.

What Is 64-bit Computing?
When reading about PCs and servers, you'll often see the CPU described by the number of bits (e.g., 32-bit or 64-bit), here's a little info about what that means.