Hardware: a practical CompTIA A+ guide
Motherboards, RAM, storage, printers, power, and component selection. Learn the mental models, common failure modes, and evidence-based troubleshooting steps.
01. Boot sequence and failure isolation
A PC that shows no sign of power is different from a PC that receives power but fails POST. For no power, verify wall outlet, power cable, PSU switch and connection. For no POST, look for diagnostic LEDs/beep patterns, then inspect seating of RAM and power connections. For no boot device after POST, inspect storage detection and firmware boot order. Avoid reinstalling Windows before verifying that the drive is detected.
02. Memory and compatibility
DDR4 and DDR5 are electrically and physically incompatible. DIMMs normally fit desktops; SO-DIMMs are common in laptops. Check generation, capacity, firmware support, and matched slots for multi-channel configurations. ECC RAM detects/corrects certain errors but requires platform support. Instability immediately after upgrading RAM strongly suggests seating, compatibility, or memory settings.
03. Storage tradeoffs
SATA SSDs use the SATA interface; NVMe SSDs normally communicate over PCIe. M.2 describes the connector/form factor, not necessarily the protocol—some M.2 devices are SATA. An HDD clicking or producing SMART errors calls for immediate data protection rather than repeated heavy diagnostics. RAID can improve performance or resilience depending on level, but it is not a backup. RAID 0 has no redundancy; RAID 1 mirrors; RAID 5 uses parity; RAID 10 combines mirroring and striping.
04. Power and thermal faults
An undersized or defective PSU may reset under GPU load. Thermal shutdown often correlates with CPU/GPU load, failed fans, dust, obstructed vents, or poor cooler contact. Inspect temperature trends before attributing the symptom to Windows. A UPS provides short-duration backup power, not indefinite runtime.
05. Printer symptom mapping
Faded output may suggest toner depletion; streaks and periodic marks can indicate drum or rollers; smearing that rubs off may indicate fusing issues. A paper jam can be caused by pickup rollers, damaged paper paths, or media mismatch. Always follow hot-component and electrical safety procedures.
Apply the lesson: real support cases
A machine freezes only when a high-end GPU is under load. Check PSU headroom, GPU power cables and cooling before replacing the OS.
A PC boots from SATA but a new M.2 SSD does not appear. Verify motherboard slot support for SATA versus NVMe and applicable BIOS settings.
These are original explanatory notes aligned to the named exam domains; review the current official objectives for exact scope. The mock exam is practice only and is not scored on CompTIA's scale.