CPU-Central Processing Unit, The CPU is the brain of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.

The two biggest manufacturers of PC CPU chips are those made by Intel and AMD other CPU makers
include Motorola, Via, and Cyrix

Central Processing Unit (The Brain of the Computer)

Two typical components of a CPU are:

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

CPU Terminology

Clock speed: Given in megahertz (MHz) or higher (GHz), the clock speed determines how many instructions per second the processor can execute. Also called clock rate, the speed at which a microprocessor executes instructions. Every computer contains an internal clock that regulates the rate at which instructions are executed and synchronizes all the various computer components. The CPU requires a fixed number of clock ticks (or clock cycles) to execute each instruction. The faster the clock, the more instructions the CPU can execute per second.
Clock speeds are expressed in megahertz (MHz), 1 MHz being equal to 1 million cycles per second.
1 MHz = 1 million clock cycle
1 GHz = 1 billion clock cycle

Bus Speed

The speeds in which a processor can send data in a pathway. 
There measured in the following speeds listed below:
33MHz, 66MHz, 100MHz, 133MHz, 166MHz, 200MHz, 233MHz, 266MHz, 333MHz, 400MHz, 800MHz, 1600MHz, 3200MHz and 6400MHz

Bus Width 32 vs. 64 bit

Address Bus: Refers to the wires that carry specific addresses to and from the processor.

Cache: Frequently stored memory, most older CPU's have an L1 internal cache built in with an L2 external cache support chips. Newer CPU's like the pentium IV have and L1 and L2 cache built in with a L3 cache
Cache is a very fast memory that is used to hold data and instructions

VRM (Voltage Regulator Mode) Is the circuitry that sends standard level voltage to the CPU

RISC vs. CISC Reduce Instruction Set Computing vs. Complex Instruction Set Computing

Math Co Processor Ability of a CPU to perform math functions and advance calculations

Cooling Mechanism Devices use to cool a CPU (FAN, Heat Sink and Liquid Cooling) also thermal paste

Overclocking Making a CPU run faster than it should

Front Side vs. Backside Bus How the CPU communicates with the memory and the cache

Hyperthreading Is a technology developed by Intel that acts as two processors

Multicore or Dual Core, Triple Core or Quad Core
Has the capability to act as separate processor in the same CPU

Instruction set: The set of instructions that the microprocessor can execute.

Bandwidth: The number of bits processed in a single instruction.

Pipelining - Allows a new instruction to start processing while a current instruction is still being processed.

Branch Prediction - A technique that attempts to infer the proper address of the next instruction while knowing only the current one.

Superscalar execution - Adding one more execution engine in a CPU

Dynamic execution - Allows the CPU to evaluate the programs's flow and choose the best order in which to process the instructions

Registers: Temporary storage areas that hold data before and after processing by the ALU. It similar to a work table use by the CPU

Computer Packages, Slots and Sockets

SEC- Single Edge Cartridge a new CPU package that is slightly bigger with a built in fan that goes into a SLOT 1 or SLOT A socket.

AMD Athlon SEC

SLOT 1 - The form factor for Intel's Pentium II processors The Slot 1 package replaces the Socket 7 and Socket 8 form factors used by previous Pentium processors. Slot 1 is a 242-contact daughter card slot that accepts a microprocessor packaged as a Single Edge Contact (SEC) cartridge. A motherboard can have one or two Slot 1s. Some Pentium III and Celeron also use SLOT 1.

SLOT A - Similar to Intel's Slot 1 but used for AMD Athlons

Slot 2 is a 330-contact use by Intel Pentium II, III XEON found mostly on server computers

PGA-Short for pin grid array, a type of chip package in which the connecting pins is located on the bottom in concentric squares. PGA chips are particularly good for chips that have many pins, such as modern microprocessors. They go into different types of CPU sockets.

Different types of PGA

SPGA: Staggered Pin Grid Array
BCPGA: Ball Chip Pin Grid Array
FCPGA: Flip Chip Pin Grid Array
CPGA: Ceramic Pin Grid Array
BPGA-Ball Pin Grid Array

ZIF - Zero insertion force, a chip socket that allows you to insert and remove a chip without special tools.

Socket - A female connector where a CPU connects

Note * PGA and LGA fits into a socket and SEC packages fits into a slot

Other CPU packages include the following:

PAC - Pin Array Cartridge (Use in Itanium CPU's)

Land Grid Array (Newer technology replacing PGA) Use grid instead of pins


CPU Package Socket or Slot
Intel Pentium 4/Core and Celeron PGA Socket 423/478
Intel Pentium 4, Extreme, Pentium D, Celeron D, Dual Core, Core2, Duo/Extreme/Quad/Xeon LGA Socket T (Socket 775)
Intel Pentium, Core, i Series, Xeon LGA Socket H (Socket 1156)
Intel Core, i Series, Xeon LGA Socket B
(Socket 1366)
Intel iCore 7 Series



Socket B
(Socket 1366)

Socket H
(Socket 1156)
Socket 989

AMD K7 Athlon, Athlon XP, MP, Duron, Semprom, Geode, NX PGA Socket A
(Socket 462)
AMD K8, AMD Athlon 64, Semprom PGA Socket 754
AMD Athlon 64/64X2, Opteron, Phenom, X2/X3, X4, X4 II PGA Socket 939/940 or Socket AM2
AMD Athlon II, Phenom II, Semprom PGA Socket AM2+, Socket AM3
AMD Athlon 64FX, Opteron PGA Socket F
(Socket 1207)
CPU Servers and Workstations Package Socket or Slot
Intel Pentium II and Pentium III Xeon SEC Slot 2 (330)
Intel Itanium PAC Socket 418
Intel Itanium II PAC Socket 611
Intel Xeon LGA Socket 603/604
Intel Core 2, Extreme, Xeon LGA Socket J
(Socket 771)
AMD Athlon 64FX, Opteron PGA Socket F
(Socket 1207)
Socket 940


Intel CPU Chart


CPU Troubleshooting

Problems with heat (cooling mechanism FAN, Heat Sink and Liquid Cooling)

5 Minute shut down (CPU is overheating)

Listen for fan for breakdown and weird unusual noises

Computer won't start

Computer is acting erratic

Keep air case tight

CPU Compatibility (look at chart)

Overclocking (make sure you have the proper cooling mechanism to support this or you will damage your CPU)

When installing CPU be careful don't bend or break pins

Match PGA to Socket (ZIF) and SEC to Slot

ZIF (Zero Insertion Force)

Match Pin 1 to the socket or look for notches when installing CPU

Avoid ESD by grounding one's self

Make sure CPU use the proper voltages

CPU Installation

CPU package must match pin 1 with CPU Socket

Put thermal compound on CPU and install proper cooling mechanism (Fan, Heat Sink or Liquid)

CPU SEC slide in CPU slot and install proper cooling mechanism (Fan, Heat Sink or Liquid)

Special Thanks to Intel and AMD