The answer is coil whine, a high-pitched whine from the PSU under load caused by electrical resonance in the inductor coils. When current surges through these coils, they vibrate at a frequency within human hearing, producing the noise, but because the system remains stable, it is not a sign of hardware failure. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your ability to distinguish between a benign electrical phenomenon and a critical fault like a failing capacitor or fan bearing—a common trap is assuming any noise means imminent failure. Remember that coil whine is load-dependent and harmless; if the system is stable, reassure the user and move on. Memory tip: “Coil whine is fine, but a grinding sound is a ground for concern.”
220-1201 Power Supply Practice Question
This 220-1201 practice question tests your understanding of power supply. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A user reports that their computer emits a loud, high-pitched whine when under load, but is silent at idle. The system is stable. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The power supply or GPU is experiencing coil whine due to electrical resonance.
Coil whine is a common phenomenon in power supplies and graphics cards when current flow causes inductor coils to vibrate at a frequency within human hearing. It is not a sign of failure unless accompanied by other symptoms.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 fan bearing is failing, causing noise only when spinning faster.
Why it's wrong here
A failing fan would produce a grinding or rattling noise, not a high-pitched whine. Fan noise is mechanical, not electrical.
✗
The CPU cooler fan is unbalanced and vibrating against the case.
Why it's wrong here
Unbalanced fans cause low-frequency vibration or rattling, not a high-pitched whine.
✓
The power supply or GPU is experiencing coil whine due to electrical resonance.
Why this is correct
Coil whine occurs when inductors vibrate under load, producing a high-pitched sound. It is normal and not harmful.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The hard drive is making noise as it reads data during gaming.
Why it's wrong here
Hard drives produce clicking or whirring sounds, not a consistent high-pitched whine that changes with load.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Power Supply — This question tests Power Supply — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The power supply or GPU is experiencing coil whine due to electrical resonance. — Coil whine is a common phenomenon in power supplies and graphics cards when current flow causes inductor coils to vibrate at a frequency within human hearing. It is not a sign of failure unless accompanied by other symptoms.
What should I do if I get this 220-1201 question wrong?
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A technician is troubleshooting a PC that emits a high-pitched whining noise under load. The noise is coming from the power supply area. The system is stable and temperatures are normal. What is the most likely cause?
medium
A.The PSU fan bearing is failing.
✓ B.The PSU is experiencing coil whine due to electrical resonance.
C.The PSU is overheating and the thermal protection is activating.
D.The PSU has a loose internal component rattling.
Why B: Coil whine is a common phenomenon in power supplies and other components when electrical current passes through inductors, causing them to vibrate at audible frequencies. It is typically harmless and does not indicate a defect, though it can be annoying. If the system is stable, no replacement is needed.
Last reviewed: Jun 18, 2026
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