Complete Beginner's Guide to Computer Components
Core 1 (220-1101) Exam PrepThis comprehensive guide covers all essential computer hardware components you need to know for the CompTIA A+ certification exam. Each section breaks down complex concepts into easy-to-understand explanations with practical examples.
CompTIA A+ focuses on practical knowledge. As you read, try to visualize how each component works together. If possible, handle real hardware components to reinforce your learning.
The main circuit board that connects all components together
The motherboard (also called mainboard or system board) is the primary printed circuit board (PCB) in a computer. It serves as the central hub that allows communication between all hardware components including the CPU, RAM, storage devices, and expansion cards.
Houses the processor. Must match your CPU type (Intel LGA 1700, AMD AM5, etc.). Not interchangeable between brands.
Controls data flow between CPU, memory, and peripherals. Determines available features like PCIe lanes, USB ports, and overclocking support.
Usually 2-4 DIMM slots for desktop memory. Supports specific DDR generation (DDR4 or DDR5). Install in pairs for dual-channel performance.
PCIe x16 for graphics cards, PCIe x1 for sound cards, Wi-Fi adapters. Number and speed varies by motherboard.
| Form Factor | Size | Expansion Slots | Best For |
|---|---|---|---|
| ATX | 12" × 9.6" | 4-7 PCIe slots | Full-featured builds, gaming |
| Micro-ATX | 9.6" × 9.6" | 2-4 PCIe slots | Budget builds, compact systems |
| Mini-ITX | 6.7" × 6.7" | 1 PCIe slot | Small form factor, HTPCs |
Know the difference between chipset generations (Intel B660 vs Z790, AMD B550 vs X670). Higher-tier chipsets offer more features but cost more. Match your motherboard to your CPU socket!
The brain of the computer that executes all instructions
The CPU processes all calculations and instructions from programs and the operating system. It performs arithmetic operations, logic operations, and controls input/output operations. CPU performance directly impacts system responsiveness and application speed.
Measured in gigahertz. Modern CPUs: 3.0-5.5 GHz. Higher is faster for single-threaded tasks, but not the only factor.
Physical processing units. 4-16 cores common. More cores = better multitasking and parallel workloads.
Virtual processing streams. Hyper-Threading/SMT allows 2 threads per core. An 8-core CPU may have 16 threads.
Ultra-fast memory inside CPU. L1, L2, L3 levels. Stores frequently accessed data. More cache = better performance.
Thermal Design Power. Heat output in watts. Desktop: 65-125W typical. Determines cooling requirements.
Physical interface with motherboard. Must match exactly. Intel LGA 1700, AMD AM5, etc.
Never force a CPU into the socket! Bent pins on AMD CPUs or damaged socket pins on Intel boards can render components unusable. Always align carefully and let the CPU drop into place naturally.
Temporary high-speed storage for active programs and data
RAM is volatile memory that stores data currently being used by the CPU. It's much faster than storage drives but loses all data when power is removed. More RAM allows running more programs simultaneously and handling larger files.
8GB: Minimum for Windows 11
16GB: Recommended for gaming
32GB+: Content creation, VMs
DDR4: 2400-3600 MHz typical
DDR5: 4800-6400 MHz typical
Higher speed = better performance
DDR4: Current standard
DDR5: Newest, faster
Not interchangeable!
Lower is better. CL16, CL18 common. Measures delay in clock cycles. Balance speed and latency.
| Type | Use | Pins (DDR4) | Size |
|---|---|---|---|
| DIMM | Desktop computers | 288-pin | 5.25" long |
| SO-DIMM | Laptops, mini PCs | 260-pin | 2.74" long |
Installing RAM in matching pairs (same capacity, speed, brand) in specific slots enables dual-channel mode, doubling memory bandwidth. Check your motherboard manual for optimal slot configuration (typically slots 2 and 4 for two sticks).
Symptoms: Random crashes, BSOD, system won't boot
Solutions: Reseat RAM, test one stick at a time, try different slots, run MemTest86, verify compatibility with motherboard QVL
Permanent data storage: HDDs, SSDs, and NVMe drives
Technology: Magnetic spinning platters
Technology: Flash memory (NAND)
Technology: Flash via PCIe
6 Gb/s interface. Connects HDDs and 2.5" SSDs. Uses SATA data cable + SATA power cable. Max speed ~550 MB/s.
Compact form factor. Same SATA speed (~550 MB/s). Plugs directly into M.2 slot. No cables needed.
Uses PCIe lanes. Much faster than SATA. Gen3: ~3,500 MB/s. Gen4: ~7,000 MB/s. Check motherboard compatibility!
NVMe drives in expansion card form. Uses PCIe x4 slot. Professional workstations. Very fast but expensive.
Know the differences between SATA, M.2 SATA, and M.2 NVMe. Understand that M.2 is a form factor that can use either SATA or NVMe protocol. NVMe uses PCIe lanes and is significantly faster than SATA.
Converts AC wall power to stable DC voltages for components
The PSU is critical for system stability and component longevity. A quality PSU protects your hardware, runs efficiently, and operates quietly. Never cheap out on your power supply!
| System Type | Recommended Wattage | Example Build |
|---|---|---|
| Office/Basic | 350-450W | Integrated graphics, low-power CPU |
| Budget Gaming | 500-650W | Mid-range GPU (RTX 3060, RX 6600) |
| Gaming | 650-750W | High-end GPU (RTX 4070, RX 7800 XT) |
| Enthusiast | 850-1000W | Top-tier GPU (RTX 4080/4090) |
80% efficiency. Basic certification. Budget units.
82-85% efficiency. Good value. Most common for mid-range builds.
87-90% efficiency. Recommended for gaming. Good balance of efficiency and cost.
89-92% efficiency. High-end. Quieter operation, less heat.
Always buy a PSU from a reputable brand like Corsair, EVGA, or Seasonic. Look for Japanese capacitors and at least an 80 PLUS Bronze rating for reliability.
Keeps your CPU and other components at safe operating temperatures
Excessive heat reduces performance and can damage hardware. Proper cooling ensures stability and extends lifespan. Both active (fans, liquid coolers) and passive (heatsinks) cooling methods are used in PCs.
Removes heat from the processor. Can be air-based (tower coolers) or liquid-based (AIO systems).
Ensure airflow through the case. Typical setup: front intake, rear exhaust. Maintain positive pressure.
Applied between CPU and cooler to fill microscopic gaps and improve heat transfer.
Adjusts fan speeds dynamically based on temperature via BIOS or software utilities.
Understand airflow direction (intake vs exhaust) and static pressure vs airflow fans. Poor cooling can cause system throttling or shutdowns during stress.
Handles image rendering, video playback, and 3D graphics acceleration
Dedicated video memory. 4–8GB for 1080p gaming, 12GB+ for 4K or AI workloads.
Measured in MHz/GHz. Higher = faster rendering. Boost clock indicates max potential.
Modern GPUs use PCIe x16 (Gen3/4/5). Backward compatible, but performance scales with newer generations.
Requires 6-pin, 8-pin, or 12VHPWR from PSU. Check PSU wattage and connectors before installation.
For CompTIA A+, know the difference between integrated and discrete GPUs, and common output ports like HDMI, DisplayPort, and DVI.
Houses and protects all internal components while managing airflow and aesthetics
| Case Type | Supported Boards | Typical Use |
|---|---|---|
| Full Tower | ATX, E-ATX | High-end builds, water cooling, multi-GPU |
| Mid Tower | ATX, Micro-ATX | Most common for gaming/work builds |
| Mini Tower | Micro-ATX, Mini-ITX | Compact home or office PCs |
| Small Form Factor (SFF) | Mini-ITX | Portable, minimalist builds |
Choose a case that supports your motherboard form factor, GPU length, and cooler height. Good airflow is more important than RGB lights!