- A
The power supply units are failing due to moisture-related internal corrosion
Humidity can accelerate corrosion on PSU components, leading to intermittent startup failures, especially after the system has been off.
- B
The building's circuit breaker is tripping due to overload
Why wrong: If the breaker tripped, PCs would not power on at all until reset, and the problem would not be intermittent or humidity-dependent.
- C
The CMOS battery is dead on each PC
Why wrong: A dead CMOS battery causes time/date resets but does not prevent the PC from powering on.
- D
The power button is stuck on each case
Why wrong: A stuck power button would cause continuous power-on attempts, not intermittent failures, and is unlikely to affect multiple PCs.
Question 922 of 1,020
Humidity-Related Power Supply Failure in Desktop PCs
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 small office has several desktop PCs that intermittently fail to power on in the morning. The issue is more common on humid days. After checking the wall outlets, you find they are properly grounded. 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.
Quick Answer
The most likely cause is that the power supply units are failing due to moisture-related internal corrosion. When humidity is high, condensation can form inside the PSU, leading to capacitor leakage or small internal shorts that prevent the PC from powering on. This is a classic symptom of a degrading power supply, not a grounding issue, since you’ve already verified the outlets are properly grounded. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your ability to distinguish between environmental factors and electrical faults—a common trap is to blame the wall circuit or inrush current, but the humidity correlation points directly to PSU degradation from moisture. Remember the memory tip: “Damp PSU, no boot for you”—if the problem worsens on humid mornings, suspect internal corrosion in the power supply before chasing ghosts in the wiring.
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 power supply units are failing due to moisture-related internal corrosion
A failing power supply can be sensitive to humidity, causing internal shorts or capacitor leakage. Inrush current from multiple PCs on the same circuit could also be a factor, but the humidity correlation points to PSU degradation. Proper grounding eliminates outlet issues.
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 units are failing due to moisture-related internal corrosion
Why this is correct
Humidity can accelerate corrosion on PSU components, leading to intermittent startup failures, especially after the system has been off.
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 building's circuit breaker is tripping due to overload
Why it's wrong here
If the breaker tripped, PCs would not power on at all until reset, and the problem would not be intermittent or humidity-dependent.
- ✗
The CMOS battery is dead on each PC
Why it's wrong here
A dead CMOS battery causes time/date resets but does not prevent the PC from powering on.
- ✗
The power button is stuck on each case
Why it's wrong here
A stuck power button would cause continuous power-on attempts, not intermittent failures, and is unlikely to affect multiple PCs.
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.
What to study next
Got this wrong? Here's your next step.
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.
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Power Supply — study guide chapter
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Power Supply practice questions
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FAQ
Questions learners often ask
What does this 220-1201 question test?
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 units are failing due to moisture-related internal corrosion — A failing power supply can be sensitive to humidity, causing internal shorts or capacitor leakage. Inrush current from multiple PCs on the same circuit could also be a factor, but the humidity correlation points to PSU degradation. Proper grounding eliminates outlet issues.
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
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Last reviewed: Jun 18, 2026
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.
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