PC Components: Motherboards, CPUs, RAM, and Storage
The motherboard is the central hub — every other component connects to it. Form factors (ATX, mATX, ITX) determine which cases and PSUs are compatible. The CPU socket must match the processor generation: Intel uses LGA (Land Grid Array — pins on the motherboard), AMD uses AM4/AM5 (PGA or LGA depending on generation). RAM must match the slot type (DDR4 or DDR5), speed, and configuration — dual-channel requires matching sticks in the correct slots (usually A2 and B2). Storage interfaces: SATA III (up to 600 MB/s, still common for HDDs and budget SSDs), NVMe M.2 (PCIe lanes, up to 7000+ MB/s for Gen 4/5 — much faster for OS and application drives). When troubleshooting POST failures: no video with beeps = GPU or RAM; no beeps, no video = PSU or motherboard; single beep then hangs = likely OS or drive issue.
Power Supplies and Cable Management
The PSU converts AC mains power to DC voltages the PC needs: 12V (CPU, GPU, motors), 5V (older drives, USB), 3.3V (RAM, some chipset components). Wattage rating must exceed peak system draw with 20-30% headroom for efficiency and longevity. Modular PSUs let you attach only the cables you need — better airflow, cleaner builds. Key connectors: 24-pin ATX (motherboard main power), 8-pin EPS (CPU), 6+2 PCIe (GPU), SATA power (drives). A PSU tester or multimeter confirms rails are within spec (12V rail should read 11.4-12.6V). A failing PSU can cause random reboots, BSODs, or prevent POST — always swap the PSU early in troubleshooting because its symptoms mimic many other failures.
Display Technologies and Connection Types
Display types for the A+ exam: LCD (uses CCFL or LED backlight, most common), OLED (self-emitting pixels, true black, risk of burn-in), IPS (wide viewing angles, accurate colour), TN (fast response, used for gaming), VA (high contrast, slower than TN). Connection interfaces: HDMI (carries audio and video, standard for TVs and monitors), DisplayPort (higher bandwidth than HDMI, supports daisy-chaining and high refresh rates), VGA (analog-only, legacy, no longer on modern GPUs), DVI (digital or analog, transitional standard). Thunderbolt 3/4 uses USB-C connector and supports DisplayPort, USB, and PCIe simultaneously. Common display issues: dead pixels (hardware defect, usually warrantied), burn-in (OLED-specific, static image left too long), flickering (cable, driver, or refresh rate mismatch), dim display (backlight failing or brightness setting on laptops).
Printers: Types, Maintenance, and Troubleshooting
The A+ exam devotes significant attention to printers. Laser printers work through six steps: Processing (image rendered), Charging (drum coated with negative charge), Exposing (laser neutralises charged areas for toner), Developing (toner adheres to exposed areas), Transferring (toner moves to paper via transfer belt), Fusing (heat and pressure bond toner permanently). Inkjet printers use liquid ink sprayed through microscopic nozzles — they produce excellent photo output but clog if not used regularly and cost more per page than laser. Thermal printers (receipt printers) use heat-sensitive paper and have no ink — paper darkens when heated by the printhead. 3D printers (FDM) build objects layer by layer by extruding heated filament. Common laser printer problems: smudging = fuser failure, ghosting = drum not fully cleaned between passes, vertical lines = dirty or damaged drum, toner not fusing = fuser temperature too low.
Mobile Devices: Features, Connectivity, and Troubleshooting
Mobile device hardware for A+: screen types (IPS LCD vs AMOLED — AMOLED is brighter and more power-efficient for dark themes), digitiser (touch sensor layered over display — replaceable separately on some models), wireless charging (Qi standard, uses inductive coils), biometrics (fingerprint readers — under-display optical or capacitive, Face ID uses structured light IR array). Connectivity: Wi-Fi standards (802.11ax/Wi-Fi 6 is current), Bluetooth versions (5.0 for longer range, lower power), NFC (Near Field Communication — used for Apple Pay, Google Pay, tap-to-pair), cellular bands (5G uses sub-6 GHz for range, mmWave for dense urban ultra-speed). Mobile troubleshooting: battery draining fast (background app refresh, GPS, screen brightness — also battery health degrades over charge cycles), overheating (CPU throttles under sustained load or in direct sun), apps crashing (clear cache first, then data, then reinstall), GPS inaccurate (location permissions, interference, almanac needs refresh).
The CompTIA Troubleshooting Methodology
CompTIA's six-step troubleshooting process: 1. Identify the problem (gather symptoms, question users, check logs, identify recent changes), 2. Establish a theory of probable cause (question the obvious first), 3. Test the theory to determine the cause (confirm or eliminate), 4. Establish a plan of action and implement the solution, 5. Verify full system functionality and implement preventative measures, 6. Document findings, actions, and outcomes. This process is linear but iterative — if step 3 disproves your theory, return to step 2. The A+ exam frequently presents scenario questions where you must identify the next correct step in this process. A common trap: students jump straight to replacing components (step 4) without testing their theory (step 3) — the exam marks this wrong.