Understanding CPU’s
William Fitzgerald
Owen Swain
CPU Basics
• The CPU is considered the “brain” of
the computer.
• It fetches instructions from memory and
executes them.
• It runs the operating system and
applications, constantly receiving input
from the user or active software
programs.
CPU Basics
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Modern CPU’s are small and square with many short, rounded,
metallic connectors on its underside.
CPU attaches directly to a CPU “socket” (also called a “slot”) on the
motherboard.
It is inserted pin-side-down and a small lever helps to secure the
processor.
After running for even a short while, CPUs will get very hot
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To dissipate the heat, it is necessary to attach a heat sink and a
fan directly on top of the CPU.
Pins are used on the bottom of the CPU to
connect to the motherboard
A heat sink and fan must be placed on top of
the motherboard to prevent overheating
Components
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Arithmetic logic unit (ALU): performs
simple arithmetic and logical operations.
Control unit (CU): interprets instructions
from memory and converts them into
signals to activate other parts of the
computer.
Cache, which serves as high-speed
memory where instructions can be copied
to and retrieved.
Transistors
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To carry out ALU calculations, computer codes
made up of zeros and ones are stored inside a
processor through the use of transistors
Transistors: Switches, which turn on and off to
control the flow of electricity; this generates binary
code
A one is created if current passes through and a
zero if a current does not pass through.
A single CPU includes several hundred million
transistors
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Troubleshooting:
Symptoms
A failing CPU could be indicated by:
The Computer not booting, or operating
system unable to load
No display
PC may crash on startup or when running
particular software
The PC may lock up after startup.
Overheating
• A computer locking up on startup can be an
indication of overheating
• Dust is a major factor, it is a thermal
insulator, meaning that the heat will build up
in the CPU because of it
• Check the temperature of your Computer, a
larger or additional fan may be needed if it is
too hot.
• Clogged vents
Other CPU Issues
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BIOS issues:
Older BIOS can have problems with newer CPU, go to
manufacturers website and install a new bios.
Installation issues
Make sure the CPU is seated flatly, make sure the CPU cannot
fall out
Orientation: make sure that the CPU is oriented to the correct
sockets, make sure the pins match up in the CPU and the socket
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No Display: The computer will turns on but system does not
start up; the common cause of this is the wrong bus speed, you
will have to reinstall the correct CPU in this scenario
Troubleshooting
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CPUs usually do not wear out under
normal circumstances
Overall, CPUs are difficult to troubleshoot
because they are not mechanical
CPUs are very difficult for an average
person to repair
If a CPU is malfunctioning it must be
replaced; Test with another CPU first
before replacing
A+ CPU Facts
When selecting a CPU be aware that you will need to
match the motherboard and CPU. Either select a CPU
supported by the motherboard, or select a motherboard
that will support the processor you have chosen. The
following should be considered when selecting a
processor:
Hyper-threading
Manufacturer
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32-bit or 64-bit
Speed
Multi-core
Cache
Process Size
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Throttling
Mobile Processors
Virtualization
Integrated memory
controller
Cooling
Manufacturer
• Intel and AMD are the two producers of
processors used in modern PCs.
• Both work in PC systems and support
Windows software.
• Intel has a larger market share, while
AMD processors generally cost less.
• Processor performance and special
features vary between models and
manufacturers.
32-bit
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Can hold 32-bits of information at
a time.
Limit of 4GB.
Use the IA-32 instruction set
(also referred to as x86).
64-bit
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32-bit applications can run on
64-bit processors using these
methods:
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Itanium processors (Intel)
use a software layer to
translate between IA-32 and
IA-64.
ADM64 and Intel 64
processors execute both 32and 64-bit instructions in
hardware.
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Can hold 64-bits of
information at a time.
Theoretical limit of
16.8TB, although
operating system and
and hardware
limitations impose a
lower practical limit.
OS and applications
must be written for 64bits to take full
advantage of 64-bit
processor.
Applications typically
perform better on 64bit systems.
Speed
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Processors operate using an internal clock that is the
same as, or is a multiple of, the motherboard bus
speed. Speed is represented in MHZ and is also
referred to as frequency.
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You can purchase processors of the same type but
with different speed ratings.
When selecting a processor, make sure motherboard
supports the processor speed by reading the
motherboard documentation first.
Most motherboard automatically detect processor
speed. If not, you might need to use jumpers or edit
the CMOS to sonfigure processor speed.
Multi-core
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Multiple core processor has multiple processors within a single
processor package.
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Dual-core, triple-core, and quad-core processors are typical
in desktop systems.
Multi-core systems allow OS to run multiple apps at once.
Without multiple processors, apps appear to run at the same
time, but must wait their turn for processing time from th
single processor.
Some apps can be written to execute on multiple processors
at the same time.
Some motherboards use two (or more) processor sockets to
provide a multiple processor solution. Multi-core processors
use a single motherboard socket to support multiple
processors.
Cache
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Cache is memory that the processor can access directly
without the system RAM. There are three types:
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Level 1 (L1) is integrated on processor die itself and
store instructions for processor. On multi-core systems,
each processor has its own L1 cache. Some may have
two, one for instructions and one for data.
Level 2 (L2) is additional cache used for both
instructions and data. Depending on processor, L2
cache may be shared between two or more cores, or
exclusive to single core.
Level 3 (L3) is additional cache beyond L2 cache. For
multi-core systems, L3 cache is shared between all
cores.
Cache
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Be aware of the following regarding cache.
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Size of cache increases as you move from L1 to
L3, with L1 being smallest.
A processor with more cache performs better than
one with less.
Originally, only L1 cache was located on the
processor die, with L2 being on motherboard
between CPU and RAM. As technology has
advanced, L2 cache moved to processor die, with
L3 on the motherboard. Now, all three are located
on the processor.
Process Size
• Refers to the manufacturing process
used to etch transistors on silicon wafer
that become the CPU. Smaller process
size means smaller transistors, which
translates to smaller CPU die with more
transistors and less power
consumption. Process size is
expressed in microns or nanometers.
Hyper-threading
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A feature of some Intel processors that allows a
single processor to run threads in parallel, as
opposed to processing threads linearly. Hyperthreading enables a processor to execute two
threads at once. For example, on a quad-core Intel
system that supports hyper-threading, the processor
can execute 8 threads at a time.
Not the same as multi-threading. Multithreading is a
feature of an app that allows it to send multiple
threads at the same time. Apps are typically written
to support multithreading to take advantage of
multiple cores or hyper-threading features.
Throttling
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Process of modifying the operating characteristics of a
processor based on current conditions.
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Often used in mobile processors to change the operating
frequency to minimize power consumption and heat output.
Can be used in low memory conditions to slow down the
processing of I/O memory requests, processing one
sequency at a time in the order the request was received.
Processors or the operating system can shut down unused
cores in multi-core systems to conserve energy.
Some Intel processors use a Turbo Boost feature. The
opposite of throttling, Turbo Boost allows the processor to
dynamically run above its rated speed to improve
performance.
Mobile Processors
• Used in notebook computers where
portability and mobility are a concern.
Special versions of processors are built
to minimize power consumption and the
amount of heat generated.
Virtualization
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Allows a single physical machine (known as host OS) to run multiple virtual
machines. The virtual machines appear to be self-contained and separate
physical systems.
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Performed by adding a layer between physical system and OS. This
layer acts as the guest system.
Early virtualization was performed using software only. Newer
virtualization uses special instructions to supported by processor to
improve performance.
VMware is most popular virtualization solution. Microsoft has several
including Virtual PC, Virtual Server, and Hyper-V.
If you plan on using virtual solution, see if hardware support in CPU is
required. Hardware support is provided by processors with following
features:
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Intel’s Virtualization Technology (VT)
AMD’s AMD Virtualization (AMD-V)
Integrated Memory
Controller
• In traditional processor design, the
processor is connected to front side bus and
Northbridge chip. Processor communicated
with other system components through front
side bus. Smaller manufacturing size has
reduced overall size of the processor,
leaving more room on processor die for
additional cores or cache. Some processors
include memory controller on processor die
rather than in Northbridge chip, resulting in
faster memory access by processor.
Cooling
• Processors require some form of heat
dissipation system to function properly.
Without a dissipation system, a
processor will overheat and burn up in
less than a minute. Most modern CPUs
require a heat sink and a fan. Between
CPU and the heat sink, thermal paste
or thermal pad helps in the transfer of
heat from CPU to cooling unit.
Performance Facts
For a long time, processor clock speed
was used as a measure of processor
performance. This is not true of newer
processors because:
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If two processors are of same type, higher speed typically
means higher performance.
Its important to make sure the motherboard can support the
speed of your processor.
Many processors use a performance rating instead of speed
with a higher number indicating a better-performing processor.
However, performance ratings are typically only applicable
between models of the same manufacturer.
In some cases, buying a processor with double cache can
nearly double the performance.
Dual core processors offer better performance, but typically do
not double.
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Special instruction sets supported by a processor can increase
performance. Example: Hyper-threading support on Intel processors can
boost performance for specific types of operations.
Performance can be increased by modifying other system components
such as adding more RAM, using a faster disk, or improving cooling or
ventilation.
Overclocking is a feature that causes the processor to operate at a
higher speed. Overclocking is performed by those who want to get the
maximum performance from their systems.
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Overclocking can cause system instability, component famage, and
can void your warranty.
Motherboard bus, processor, and memory setting shuld eb adjusted.
Overclocking may require more voltage.
Overclocking increases heat output. May be necessary to upgrade
your cooling devices.
CPU Socket Facts
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Ensure motherboard is compatible with system CPU that you
intend to use.
Motherboard socket must match the socket of your processor.
Some motherboard accept multiple processors and will have a
socket for each one.
Processor sockets can be categorized according to how the
processor makes contact with the leads in the processor socket:
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Pin Grid Array (PGA) implement a series of pins on the
underside of the processor package in an array. The pins are
inserted into corresponding receptacles within the processor
socket on the motherboard.
Land Grid Array (LGA) socket moves connecting pins from
processor package to the socket itself. Conducting pads are
implemented on the bottom of the processor that contact the
protruding pins from processor socket.
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Some commonly implemented sockets include:
Intel
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775: Used with Intel Pentium 4, Celeron D, Intel
Pentium 4 Extreme Edition, Pentium D, Pentium
Dual-Core, Core 2 Duo, Core 2 Extreme
1155: Used with Intel Pentium 4, Celeron, Core i3,
Core i5, Core i7, Core i7 Extreme, and Xeon
processors.
1156: Used with Pentium 4, Celeron, Core i3, Core
i5, Core i7, and Xeon proessors.
1366: Used with Intel Celeron, Core i7, and Xeon
processors.
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AMD:
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940: Used with AMD Opteron and Athlon 64 FX
processors.
AM2: Athlon 64, Athlon 64 X2, Athlon 64 FX, Opteron,
Sempron, and Phenom processors.
AM2+: Used with Athlon 64, Athlon 64 X2, Athlon II,
Opteron, Phenom, and Phenom II.
AM3: Used with Phenom II, Athlon II, Sempron, and
Opteron.
AM3+: Used with Phenom II, Athlon II, Sempron, and
Opteron processors.
FM1: Used with Athlon II processor along with A-series
APUs.
F: Used with Opteron and Athlon 64 FX.
CPU Installation
Facts
Intel Chip: CPU is installed in the Socket 775 connector
AMD chip: install the processor into the white square labeled Socket AM2
Connector
https://www.youtube.
com/watch?v=vLVHF
aokdgA
More Resources
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http://www.geek.com/desktop-computerbuyers-guide/cpu/
http://educationportal.com/academy/lesson/centralprocessing-unit-cpu-parts-definitionfunction.html#lesson
http://www.youcanbuildyourowncomputer.
com/installprocessorcpu.html