CompTIA A+: Understanding Computer Hardware

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Module 4:

As a CompTIA A+ professional it’s essential to grasp the different computer hardware components that work together to make computers functional.

PC Components

Component Description
Motherboard The main PCB inside the computer.
I/O Panel Back panel
Super I/O Chip Is a class of I/O controller. It intergrates devices formerly found on seperate expansion cards.
Circuit Is a loop through which current can flow.
Drive Connections Connects drives to the motherboard.
IDE Connections A single IDE ribbon cable with a keyed connector to ensure proper connection.
Diodes Only send current in one direction
DRAM Dynamic RAM is constantly refreshed. Its single ported meaning it can only read or write at a time.
EPROM Erasable, programble ROM
SRAM Static RAM is used to get information from the cache memory, speeding everything up.
North Bridge Communicates data from CPU to ram
South Bridge Handles USB connection
CMOS RAM Complimentary metal oxide semiconductor is the area where a computer stores its configuration.
VRAM Video RAM is the memory used for the video card accelerators to store the values of pixels making it faster to refresh. VRAM is dual ported so it can Read and Write at the same time.
BIOS Flash The ability to flash the BIOS chip with updated firmware.
BIOS Chip Basic input output system.
RAM Read access memory.
ROM Read only memory.
CPU The central processing unit.
Heatsink Keeps CPU cool.
Fan Connection There are 3 types of fan connection. 2-pin, 3-pin, or 4-pin.
CMOS battery Holds charge for the CMOS RAM
Capacitor A Capacitor stores electrical energy.
DIMM Memory Dual in-line memory module.
Power Connection The connection for the computers main power source.
Adapter cards Sound, audio and video, microphones
PCI card Peripheral component interconnect
AGP Advanced graphics port
UEFI Unified Extensible Firmware Interface is going to replace CMOS in the future. To access the UEFI, in search bar type UEFI hit enter. Click restart now to enter UEFI settings.

Understanding Motherboards

  • Know the function of the motherboard.
  • Know the form factors.

Understanding Memory

  • RAM (Read Access Memory)
  • ROM (Read Only Memory)
  • DRAM (Dynamic RAM) – Constantly refreshed memory.
  • SRAM (Static RAM) – Handles cache memory.
  • CMOS RAM – Here is where the computer holds its configuration.
  • VRAM (Video RAM) – Stores values of pixels for faster refresh rates.
Memory modules can be:

  • Single or Double sided.
  • Single or Dual channel.
  • Buffered or Unbuffered.
  • Cached.

Cache memory allows computers to create caches at various levels of the network. It’s usually faster and much more expensive. The three main levels of cache memory are: L1 cache, L2 cache, L3 cache.

  • L1 or primary cache is extremely fast and very small. Its usually embedded in the processor chip as CPU cache.
  • L2 or Secondary cache is more capacious then L1. It can be embedded in the CPU or on a separate chip or core predecessor and have a high-speed system bus connecting the cache and CPU. This prevents traffic slowdown on the main system bus.
  • L3 cache is specialized memory developed to improve the performance of L1 and L2. L1 and L2 memory can be much faster than L3 but L3 is twice as fast as DRAM.

Error Checking Memory

Parity Vs. Non-Parity

  • Parity memory verifies the information stored in memory is actually what was read from a later time.
  • Non-Parity memory does not perform any error checking.

ECC Vs. Non-ECC Memory

  • ECC Memory acts as error detection and correction.
  • Non-ECC Memory does not have an error detection feature.

Looking For Memory Errors

  • Open Task Manager, select Performance.
  • Select Memory and check its usage.
  • Select Open Resource Monitor. Look for high levels of activity,
  • Ignore the spikes but look for constant high performance.
  • Select CPU to end any troubled services.
  • Select Memory and select commit to bring the higher usage services to the top.

The resource monitor is a good place to start when debugging a computer.

The North Bridge

  • The north bridge handles data between the CPU to memory.

The South Bridge

  • The south bridge handles data between the CPU to USB, IDE, PCI.

Front and Side Panels

  • Audio connections
  • Drive activity light
  • Power light
  • On/Off button
  • USB connections

Cache Memory

Level Description
Level I or L1 Is directly built into the microprocessor.
Level II or L2 Is specialized, high performance computer memory which used to be found on the motherboard,
but now found on the die of the CPU.
Level III or L3 Is specialized and can be found on the motherboard and special processors.

RAM Slots

  • Memory slots and sockets.
  • DIMM.

Expansion Slots

  • Allows you to expand in functionality using the expansion slots.

Bus Architecture

  • PCI
  • AGP
  • PCI-X
  • PCI Express
  • AMR (Audio Modem Risers)
  • LNR

Connections and Ports

Connection/Port Description
Keyboard PS/2 previously. Now typically connects via USB.
Mouse PS/2 previously. Now typically connects via USB.
Serial 1 Serial port is the generic term for any port that’s sends data in a serial fashion.
USB Universal Serial Bus. The handy connection that connects almost every external device to the PC.

Optical Drives

  • Floppy Disk
  • CD
  • DVD
  • Blu-Ray


It’s important to be familiar with processors and the related terminology.

Type Description
Processor speed The speed at which processor executes a command, Its measured in Megahertz and Gigahertz.
Data bus Is the pathway between the processor and the memory. The processor accesses the memory constantly, so the data bus is dedicated full-time to this operation. Transfers data in bits.
Cache memory Cache memory provides faster memory retrieval by storing it in the cache in-case it is needed later.
Registers Provide storage within processors to temporarily provide information and data to be able to manipulate it at a later time.
Math processors Math processors are used to perform and execute calculated mathematical functions, so the CPU can concentrate on logical functions.NPU calculates mathematical functions. CPU calculates logical functions. GPU calculates video operations.
Hyper-threading Allows a processor to act as 2 processors executing simultaneous threads.
Multi-core processing Combines independent processors into one single processing chip which allows you to execute multiple threads at the same time without using hyper-threading.
Address Bus Uses a read/write system which is referenced by location. When storing information into system memory, the processor provides a location address with the information that is stored. A 32-bit processor has to make 2 trips to provide 64 bits of data, the trip back and forward is known as the Cycle Clock.
The less trips made the better efficiency.
Type Description
Registers Are storage areas within the processor used for temporarily storing data future use.
Cache Memory Information stored in the processors high speed memory.
Virtualization Virtual Machines running Operating systems within an operating system.
GPU Graphics Processing Unit. Provides video calculations and processing of graphical operations.
Throttling The CPU reduces processing speed when it senses overheating.
Overclocking Causing hardware to perform faster than the rated speed.
Clock multiplying The processor will run faster than the motherboard. The motherboard speed is as important as the advertised speed of the processor.

Chip Packaging

How a computer chip is constructed and delivered to the consumer.

  • Shape and Form
  • Dual inline package (DIP)
  • Pin Grid Array (PGA)
  • Land Grid Array (LGA)
  • Single Edge Contact (SEC)

Processor Sockets

  • Compatibility
  • Determine which socket exists
  • Purchase Correct Type
  • Match the voltage of the board
  • Sockets are labelled by type along the side of the socket

There is a vast amount of socket and slot types, double check. You can Google “List of processor sockets”.

Processor Motherboard Speed Multiplier Processor Speed
Pentium90 60 1.5 90
Pentium100 60 1.5 99
Pentium150 60 2.5 150

Additional Core Processors

  • Included dynamic execution
  • Multiple branch prediction
  • Data flow analysis
  • Speculative execution

Pentium Pro, Pentium II, III, 4, M, Celeron, IntelCore 2, Atom, i3, i5, i7, Athlon, Turion.

Hard Disks

Hard disks are a common feature in PC workshops.

Trouble shooting tools:


IDE Devices

Integrated drive electronics inverts signals from the hard disk to something the computer understands.

EIDE Devices

The enhanced IDE allows data speeds of 60mbs, and the controllers are integrated into the drive themselves.

Removable storage

  • SSD
  • External HDD
  • Thumb and Flash drives
  • SD cards


Small Computer Systems Interface is a set of standards for physically connecting and transferring data between computer and peripheral devices. The SCSI standards define commands, protocols, electrical, optical and logical interfaces.

The SCSI is most commonly used for HDD and tape drives, but it can connect a wide range of other devices, including scanners and Cd drives, although not all controllers can handle all devices. It’s not available in small computers. Its only in server hardware or stand-alone disk arrays. This is Important for the A+ professional to know. The host adapter is an expansion card so you can chain SCSI devices off the adapter.

Basically, the host adapter is the brain of the SCSI bus and acts as the controller. for the SCSI bus. Its responsible for sending and receiving information to and from the SCSI bus within the system.
In addressing, each external device is assigned an internal address. The SCSI controller knows each address of connected devices.

SCSI Cabling Transfer Speeds

  • The wider the cable, the faster data is transferred.
  • LVD or Ultra 2 SCSI has a data speed of 80mbs
  • SCSI 1 has 5mbs
  • SCSI 2 has 20MBS (Fastwide)
  • Ultra SCSI is 20mbs

SCSI will support 8 devices with a bus that includes a card counting as a device.


Serial ata (Sata) IDE technology has been around for many years. Sata is a newer hard drive technology which offers great speeds. Sata hardware interface is hot swapable.

Sata versions:

  • Sata version 1 = 150mbs
  • Sata version 2 = 300mbs
  • Sata version 3 = 600mbs

Sata cables can be 39 inches long.


Redundant Array of Independent Disks. RAID is an important concept because most computers employ raid hardware, this will handle all background operations to keep things running.

Version Description
Raid 0 Has 2 or more hard drives bound together in a single disk volume.
Raid 1 Has a Mirrored volume disk where every mirror of every disk has an input output operation on the primary disk and then to a separate disk known as the mirror disk.
Raid 5 Blends the benefits of Raid 0 with the redundancy of Raid 1.

Power Supply and Voltage

Power supply units or PSU convert AC current to DC current and usually comes in 3.3v, 5v, and 12v.

  • Uninterruptible power supply units come with a battery back-up.
  • Surge Protectors protect your hardware from sudden surges of power.
  • Brown out is a sustained lack of power.
  • Black out is a total power loss.

You need to be able to identify the different power supply types.

Type Description Wattage
Cfx v1.3 Compact supply 220-300w
Lfx V1.1 Low profile supply 180-260w
Sfx V3.1 The smallest supply 160-300w
Tfx v2.2 A thin supply 180-300w

You need to be familiar with:

  • Amps
  • Ohms
  • Volts
  • Watts

Power supply uses:

  • Converts voltage
  • Over current protection
  • Input supply voltage
  • DC voltage regulation
  • Input under voltage
  • Energy star designation

Power Consumption

Device Power utilization
AGP video card 30-75w
AMD Athlon 64 dual core 3ghz 125w
CPU fan 2w
CD drive 25w
USB device 5w


The common ports can be found on the back panel of the computer.

Port Type Description
Serial Ports Deliver data sequentially down a single wire.
In serial ports 8bits of data are converted into an analog signal called a baud.
The baud rate is similar to the number of tones that are made on the wire and how many are made a second.
These were used on older computers to connect devices like printers.
Parallel Ports Send data over multiple wires simultaneously.
Universal Serial Bus Uses Plug and Play technology which makes things easy to swap around.
USB is far faster than its predecessors.
Thunderbolt Is a newer technology.
Its found in many laptops and PC’s today.
Thunderbolt is also known as USB-C.
It provides 15w of power for devices and 100w for charging your laptop.
It can transmit data at 40gbs.
It can connect an external GPU.
It can even connect a monitor.
VGA Port The older way to connect a monitor to a PC.
HDMI Port Today’s way of connecting a monitor to a Desktop PC.
Keyboard and Mouse Ports The older way to connect the keyboard and mouse.
Today we just use USB.

Manufacturers today, are trying for a “Legacy Free” PC, meaning it will have no serial or parallel ports, just USB and HDMI.


Cable Type Description
Ribbon Cable Are used to connect internal hardware inside a PC like a hard disk or optical drives.
Ribbon cables are made up of multiple cables sat side by side flat.
One side has a color strip, this indicates wire 1.
The Ribbon cable has key connections to prevent it being inserted incorrectly.
Coaxial Cables Thick coaxial is rigid and can carry 10mbs of data over a distance of 500m.
Thin coaxial is flexible and can carry 10mbs of data over around 185m.
Fiber Optic Allows very fast data transfer over long distances.
This is the most expensive way to transfer data.
Null Modem Cables Eliminates the need for a modem to connect devices together.
RJ-11 Commonly used for telephones.
RJ-45 Used for voice grade circuits.
They are used in networking to connect elements of the network together.
Larger than RJ-11 cables.

Twisted Pair and Un-Shielded Twisted Pair

Twisted Pair and Un-Shielded Twisted Pair Have multiple wires twisted through the cable, the more twists they have the faster the transfer rate.

Twisted Pair Type Description
CAT 1 Speakers and devices which require an audio signal
CAT 2 Analog telephone applications with low-speed transmissions
CAT 3 Ethernet and data networking
CAT 4 Provides 16mps Token ring data
CAT 5 Provides 100mps and reduces cross talk
CAT 6 Provides 10gps by increasing frequency
CAT 7 Provides 100gps and frequencies up to 600mhz

Video Adapters

Video Cards

  • Data is sent to the video card.
  • Video chip writes data to memory.
  • The data is sent to the DAC (Digital Analog Converter).
  • Signal is sent to the monitor.
  • The monitor displays the signal

Video Standards

  • CGA (Color Graphics Adapter)
  • EGA (Enhanced Graphics Adapter)
  • MDA (Monochrome Display Adapter)
  • VGA (Video Graphics Array)
  • SVGA (Super VGA)
  • XGA (Super and Ultra)

Type Colors Resolution
CGA 4 320×200
MDA 2 640×200
EGA 16 640×350
VGA 16 640×480
SVGA 16,000,000+ 1280×1024
XGA 64,000 1400×1050

Video Connectors

  • DVI (Digital Video Interface)
  • HDMI (High Definition Multimedia Interface)
  • VGA (Video Graphics Array

Installing Video Cards

  • Turn off and unplug the computer
  • Open casing for access
  • Remove existing video card
  • Firmly insert new video card
  • Secure if needed
  • Close casing, power up, and test.


Types of Display

  • Cathode Ray Tube (CRT)
  • Liquid Crystal Display (LCD)
  • Light Emitting Diode (LED)

Display Features

  • Anti-Glare
  • Brightness
  • Colour Depth
  • Contrast Tube
  • Resolution

Clients may inadvertently adjust these settings, so it’s good to know what they do.

Feature Description
Brightness Brightness or Lumens, adjusts the amount of light the display can give.
Color Depth Defines the number of bits that are used to make a single pixel. The greater
the bit depth, the larger the monitors palette.
Contrast Rate Measures the brightness of different colors and uses a ratio to describe quality. Example:3000×1 would be a high quality.
Resolution Defines how many pixels can be supported on the screen.
The higher the resolution the better the picture.

Multiple Displays

You can use more than one monitor to maximize workspace, you may need to install an additional Video card to do so. Plug a monitor into each video card and make sure the correct drivers are installed for each monitor. Then enable Multi Display support.

Common Issues

  • No image available.
  • Overheating cause shutdown.
  • Incorrect color patterns.
  • Dead pixels.


A common client issue is printers. When working with printers you will need to look at:

  • Drivers
  • Paper feed
  • Networking
  • User error
  • Preventative maintenance
  • Display error codes
  • Connections
  • Safety issues

Drivers sometimes need updating. Sometimes it could just be a simple jam. Network sharing is something you need to get comfortable with.

Types of printer:

  • Laser
  • Ink jet
  • Dot Matrix
  • Multi-function
  • Cloud based
  • Thermal

Laser printers print one page at a time, very quickly. Has the highest quality.

Ink jet printers are the second most common type of printer. Has a high quality and is relatively inexpensive.

Dot matrix printers are not used often anymore. It would print by using many dot form the print.

Multi-function printers allow you to combine functions such as scanning and faxing.

Cloud based printers allow you to print internally to your PC from anywhere.

Thermal printers use special paper and a stylus pin to print on a print head.

Printer Parts

Most printers consist of the same parts.

  • Print head
  • Feeder
  • Roller
  • Duplexing assembly
  • Carriage and belt
  • Heating element
  • Paper tray

Network Connection

The Common Path: \PC-Name\Share-Name

Wireless network connection is better than a USB connection. The advantage of this is you can connect up to 127 devices in a chain with a transfer rate of 5gps.

Laptop Components

  • Display
  • Power button
  • Keyboard
  • Display latch
  • Ports
  • Palm rest
  • Touch pad

Things to check before inspecting a laptop:

  • Speed (GHZ)
  • Storage
  • RAM
  • Hard drive
  • Processor

Laptop Operations

  • Battery types
  • Battery handling
  • Battery performance
  • Stand-by and sleep modes
  • AC adapters
  • LCD panel displays

Common Problems

  • Battery or power supply
  • Toggle function keys
  • Unplug peripheral devices
  • Verify connections
  • Check the wireless switch
  • Verify software configuration
  • Replace PSU, if needed

Do an inventory of the customers device before you proceed to work on it, look for damage. Always look online for service manuals. Batteries are the most common issue. Always work in a large, clean area. Document your process and findings. Document resolutions to problems. Sometimes the laptop will need to be sent back to the manufacturer to be repaired. Always check the warranty.

Best Guidance: Don’t try to service parts you can’t see or are not accessible without specialist tools.

Understanding these hardware components is fundamental for building, upgrading, or troubleshooting computers. Whether you’re a professional technician or an enthusiast, a solid grasp of these components is essential for working effectively with computer systems.

You can find all of our CompTIA A+ guides here:

We also have guides for the CompTIA Security+ here:


Hirens Boot CD:

Luke Barber

Hello, fellow tech enthusiasts! I'm Luke, a passionate learner and explorer in the vast realms of technology. Welcome to my digital space where I share the insights and adventures gained from my journey into the fascinating worlds of Arduino, Python, Linux, Ethical Hacking, and beyond. Armed with qualifications including CompTIA A+, Sec+, Cisco CCNA, Unix/Linux and Bash Shell Scripting, JavaScript Application Programming, Python Programming and Ethical Hacking, I thrive in the ever-evolving landscape of coding, computers, and networks. As a tech enthusiast, I'm on a mission to simplify the complexities of technology through my blogs, offering a glimpse into the marvels of Arduino, Python, Linux, and Ethical Hacking techniques. Whether you're a fellow coder or a curious mind, I invite you to join me on this journey of continuous learning and discovery.

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