Laptop Hardware & Components

CompTIA A+ Core 1 (220-1101) • Domain 1.0 Mobile Devices

Key Concepts: SO-DIMM Batteries Displays Keyboards Docking Stations

Laptop vs Desktop Components

Laptops use specialized, compact versions of desktop components. Many parts are proprietary or soldered, limiting upgradeability.

Component Upgradeability

RAM (SO-DIMM)

Storage (M.2/2.5")

WiFi Card

Battery

CPU

GPU

Display

Keyboard

■ Often upgradeable ■ Usually soldered/proprietary

Modern Trend: Ultrabooks increasingly solder RAM and storage for thinner designs. Always check specs before purchase!

Laptop Memory (SO-DIMM)

SO-DIMM (Small Outline DIMM) is the compact RAM form factor for laptops.

Generation	Pins	Voltage	Speed Range
DDR3 SO-DIMM	204 pins	1.5V / 1.35V	800-2133 MHz
DDR4 SO-DIMM	260 pins	1.2V	2133-3200 MHz
DDR5 SO-DIMM	262 pins	1.1V	4800-6400+ MHz

A+ Exam Tip: SO-DIMMs are roughly half the length of desktop DIMMs (~67mm vs ~133mm). Always match the DDR generation to the laptop's specifications.

Laptop Batteries

Battery Types

          Lithium-Ion (Li-ion)

          Most common laptop battery type

          Good energy density, no memory effect

          Lithium-Polymer (Li-Po)

          Flexible form factor

          Used in ultrabooks, lighter weight

Battery Specifications

Spec	Meaning
Wh (Watt-hours)	Total energy capacity (higher = longer runtime)
mAh (milliamp-hours)	Charge capacity at a specific voltage
Cells	Number of battery cells (3-cell, 6-cell, etc.)
Charge Cycles	Full discharge/recharge cycles before degradation

Battery Safety: Never puncture, expose to heat, or use damaged batteries. Swollen batteries should be professionally replaced immediately!

Laptop Displays

Display Technologies

Type	Pros	Cons
TN (Twisted Nematic)	Fast response, affordable	Poor viewing angles, colors
IPS (In-Plane Switching)	Great colors, wide angles	Slower response, higher cost
VA (Vertical Alignment)	High contrast, deep blacks	Slower response than IPS
OLED	Perfect blacks, vibrant colors	Burn-in risk, expensive

Display Components

          LCD Panel

          The display screen itself

          Various technologies

          Backlight

          LED edge-lit or direct-lit

          OLED is self-emitting

          Inverter (Legacy)

          Powers CCFL backlights

          Replaced by LED

Input Devices

Keyboard Types

Membrane: Most common, quiet
Scissor-switch: Low-profile, laptop standard
Mechanical: Gaming laptops
Backlit: LED illumination

Pointing Devices

Touchpad: Multi-touch gestures
Pointing stick: ThinkPad TrackPoint
Touchscreen: Direct finger input

Keyboard Replacement: Some laptops have user-replaceable keyboards (secured by screws). Others require motherboard removal - check repair guides first!

Laptop Expansion & Docking

Port Replicators vs Docking Stations

          Port Replicator

          Adds ports via USB/Thunderbolt

          Portable, universal, no proprietary connector

          Docking Station

          Full desktop experience

          May use proprietary connector, more features

Common Laptop Ports

Port	Purpose
USB-C / Thunderbolt	Data, display, charging (multi-purpose)
HDMI / Mini-HDMI	External display output
USB-A	Legacy peripherals
SD Card Slot	Memory card reader
3.5mm Audio	Headphones/microphone
Kensington Lock	Physical security tether

Wireless Components

          WiFi Card

          Usually M.2 or mini-PCIe

          Often upgradeable

          Bluetooth

          Often combined with WiFi

          Same card, dual-mode

          Cellular (WWAN)

          4G/5G mobile data

          Requires SIM card, optional

          NFC

          Near-field communication

          Tap-to-pair, payments

Antenna Wires: WiFi antennas are typically routed through the display hinge to the lid. Black and gray wires for different bands.

Common Laptop Repairs

Component	Difficulty	Notes
RAM Upgrade	Easy	Usually accessible via bottom panel
Storage Upgrade	Easy	M.2 or 2.5" drive swap
Battery Replacement	Moderate	May require bottom case removal
Keyboard Replacement	Moderate	Varies by model significantly
Screen Replacement	Advanced	Bezel removal, delicate cables
Motherboard Repair	Expert	Micro-soldering, specialized tools

Knowledge Check

Q1: How many pins does a DDR4 SO-DIMM have?

Q2: What type of battery is most common in modern laptops?

Q3: Which display technology offers the best viewing angles and color accuracy?

Q4: What is the difference between a port replicator and a docking station?