CompTIA A+ Core 1 (220-1201)HardwareMedium
A technician is troubleshooting a desktop computer that fails to boot. Upon inspection, the technician notices that the system's power LED flickers, and the CPU fan briefly spins before stopping. No display output is observed. What is the most likely cause of this issue?
- ACorrupted BIOS firmware
- BFaulty power supply unit (PSU)
- CLoose data cable to the hard drive
- DDamaged graphics card
Show answer & explanationAnswer & explanation
Correct answer: B. Faulty power supply unit (PSU)
The symptoms of flickering power LED and a CPU fan briefly spinning before stopping strongly suggest that the power supply unit (PSU) is failing to deliver stable and sufficient power to the system, causing it to attempt to start but immediately shut down or cycle.
Why the other options are wrong
- A. Corrupted BIOS firmware would typically prevent any POST or boot attempt, but not usually manifest as flickering power and brief fan spin-up/shutdown.
- C. A loose hard drive data cable would prevent booting into the OS but would not stop the CPU fan or cause power flickering.
- D. A damaged graphics card would typically prevent display output but would still allow the system to power on and fans to spin normally, often with beep codes.
Power Supply Unit (PSU) Symptoms
Common indicators of a failing power supply unit include intermittent power, unexpected shutdowns, system instability, or complete failure to power on.
- Flickering power LEDs or fans briefly spinning are strong indicators.
- Can manifest as random reboots or system freezes.
- Often mistaken for other component failures, but specific power symptoms point to the PSU.
Memory trick: When it won't boot, check 'P.C.R.D.' - Power, Cables, RAM, Display.