4.1.1. Troubleshooting Motherboards, RAM, CPUs, and Power
💡 First Principle: To diagnose boot failures, you must interpret audible (beep codes) and visual (POST errors, BSOD) cues to form a primary theory, then test that theory by reseating components before replacing them.
Scenario: A user reports their 3-year-old PC randomly shuts down, but only when they are exporting large video files. They mention it doesn't happen during normal web browsing. The case feels warm to the touch. You check Event Viewer and see "Kernel-Power" critical errors but no other specific cause.
Technician's Diagnostic Path:
- Initial Theory: The symptoms (shutdown under heavy load, heat) point strongly to either an overheating issue or an insufficient/failing Power Supply Unit (PSU).
- Test for Overheating:
- Plan: Install a temperature monitoring utility (e.g., HWMonitor).
- Action: Ask the user to start a video export and monitor the CPU and GPU temperatures.
- Expected Result: If temperatures climb above 90-95°C before shutdown, overheating is the confirmed cause.
- Test for PSU Failure:
- Plan: If temperatures are normal, the PSU may not be providing stable power under load.
- Action: Use a PSU tester to check basic voltage rails. For a more definitive test, swap the PSU with a known-good unit of appropriate wattage.
- Expected Result: If the system is stable with the new PSU, the original PSU is faulty.
⚠️ Common Pitfall: Forgetting to check for swollen or leaking capacitors on the motherboard. This is a clear sign of a failing motherboard that needs to be replaced.
Reflection Question: Justify why you would test for overheating before replacing the PSU. Design a 3-step plan to resolve the issue if you confirm the cause is CPU overheating.