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220-1201 Practice Question: A technician is troubleshooting a PC that powers…
A technician is troubleshooting a PC that powers on for a few seconds then shuts off. The technician removes the 24-pin connector and jumps the green wire to a black wire; the PSU fan spins and stays on. What does this indicate?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The motherboard has a short circuit causing the PSU to shut down.
The paperclip test confirms the PSU can power on independently. If the fan runs continuously, the PSU is likely functional. The issue is probably elsewhere, such as a short on the motherboard or a faulty component drawing too much power.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The power supply is definitely faulty and should be replaced.
Why it's wrong here
The paperclip test, which involves shorting the PS_ON# pin to a ground pin on the 24-pin ATX connector, successfully powered on the PSU and its fan. This indicates that the power supply unit itself is functional and capable of delivering power. Therefore, replacing the PSU at this stage would be an incorrect diagnostic step, as the issue likely resides with a component connected to it, not the PSU itself.
- ✓
The motherboard has a short circuit causing the PSU to shut down.
Why this is correct
A short circuit on the motherboard or a connected peripheral draws excessive current, exceeding the power supply unit's (PSU) rated capacity for that rail. Modern PSUs are equipped with Overcurrent Protection (OCP) and Short Circuit Protection (SCP) features designed to detect such anomalies. When triggered, these safety mechanisms immediately shut down the PSU to prevent damage to itself and other components, explaining why the PC powers on briefly before shutting off.
- ✗
The CPU is overheating and triggering thermal shutdown.
Why it's wrong here
CPU overheating typically requires a sustained period, usually several minutes, for temperatures to rise to critical levels before the system's thermal protection mechanisms initiate a shutdown. An immediate shutdown, occurring within seconds of powering on, is highly indicative of an electrical fault, such as a short circuit or an overcurrent condition, rather than a thermal issue. Therefore, CPU overheating is an unlikely cause for an instantaneous shutdown.
- ✗
The power supply fan is defective, causing it to overheat and shut off.
Why it's wrong here
The power supply fan was observed spinning during the paperclip test, confirming its operational status and ruling out a defective fan as the cause. Even if the fan were defective and the PSU began to overheat, thermal shutdown mechanisms in a PSU typically require a significant duration, often several minutes, for internal temperatures to reach critical thresholds. An immediate shutdown within seconds of power-on is inconsistent with a thermal issue.
Go deeper
Related to this question
Learn chapter
Motherboard Components and Form Factors
Key term
Motherboard
The main circuit board inside a computer that connects all components so they can communicate with each other and receive power.
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1201 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1201 exam.