Question

Difficulty: MediumMotherboard, RAM, CPU, and Power Issues

A technician is troubleshooting a desktop computer that repeatedly powers down unexpectedly during operation and occasionally fails to complete the Power-On Self-Test (POST). The technician suspects an unstable power supply or internal power delivery fault. In what order should the technician execute the following diagnostic and corrective steps according to standard hardware troubleshooting procedures?

  1. 1Perform a physical inspection of internal power cables, motherboard headers, and capacitors for loose connections or distended/leaking components.
  2. 2Disconnect non-essential peripherals, secondary storage drives, and add-in cards to strip the system down to a minimal POST configuration.
  3. 3Measure output voltages on the +12V+12\text{V}, +5V+5\text{V}, and +3.3V+3.3\text{V} power rails using a multimeter or dedicated power supply tester.
  4. 4Swap the suspect power supply unit with a known-good replacement unit of equivalent or higher wattage capacity.

Answer

The correct diagnostic sequence begins with a visual inspection of internal cables and capacitors, followed by isolating system power draw to a minimal POST configuration, testing PSU rail voltages (+12V+12\text{V}, +5V+5\text{V}, +3.3V+3.3\text{V}) directly, and finally replacing the faulty PSU with a known-good spare.
Standard CompTIA troubleshooting requires starting with simple visual inspection (checking cables and checking for distended capacitors), followed by component isolation to a minimal POST build, quantitative voltage testing with a multimeter or PSU tester, and finally replacing the verified faulty component with a known-good power supply.

Step-by-Step Solution

1
Visually inspect internal cables, power connectors, and motherboard components.
Identifies loose 24-pin ATX or 8-pin EPS power cables or blown/distended motherboard capacitors before applying electrical tests.
CompTIA troubleshooting methodology always prioritizes quick, non-invasive visual checks and verifying physical power connectivity.
2
Disconnect non-essential expansion cards, storage drives, and external peripherals.
Establishes a minimal functional POST hardware configuration (CPU, motherboard, one RAM module).
Eliminates potential short circuits or excessive wattage demands caused by secondary hardware components.
3
Test power supply unit rail voltages using a multimeter or PSU tester.
Verifies whether +12V+12\text{V}, +5V+5\text{V}, and +3.3V+3.3\text{V} power outputs are operating within ATX specification limits.
Determines if the power supply unit is malfunctioning prior to removing and replacing system hardware.
4
Install a known-good power supply unit.
Restores consistent system power delivery and verifies complete POST and operational stability.
Replaces the confirmed faulty component to finalize problem resolution.

Key Concept

Sequential diagnostic methodology for motherboard, power supply, and hardware failure isolation.
Estimated Time:1m 30s
Rate this question