- A
The motherboard voltage regulator is failing.
Why wrong: A failing VRM would typically cause instability on the CPU or memory, but the low +12V reading is measured at the PSU output, indicating the source is the PSU itself.
- B
The power supply is failing and needs replacement.
A +12V reading of 11.2V is below the ATX tolerance of 11.4V, indicating the PSU cannot maintain proper voltage, likely due to aging capacitors or other internal faults.
- C
The system is drawing too much current, causing voltage drop.
Why wrong: While excessive load can cause voltage drop, the PSU should still regulate within spec if it is functioning correctly; a healthy PSU would shut down or limit current before dropping this low.
- D
The AC input voltage is too low.
Why wrong: Low AC input would affect all rails proportionally, but the +5V and +3.3V rails are within spec, so the issue is isolated to the +12V rail regulation.
Quick Answer
The answer is a failing power supply that needs replacement. This is correct because the +12V rail reading of 11.2V falls below the ATX specification’s minimum of 11.4V (a ±5% tolerance), and such a low voltage under load directly explains random shutdowns, as the CPU and GPU rely on stable +12V power to operate. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your ability to interpret multimeter readings against ATX standards and distinguish a failing PSU from other causes like overheating or driver issues. A common trap is assuming all rails must be out of spec, but here the +5V and +3.3V rails are within tolerance, so the +12V drop alone points to the power supply. Remember the memory tip: “12V is the lifeline—below 11.4V, it’s time to replace.”
220-1101 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 technician is troubleshooting a PC that shuts down randomly after a few minutes of use. The technician measures the +12V rail with a multimeter and gets 11.2V. The +5V rail reads 4.9V, and the +3.3V rail reads 3.2V. What is the most likely diagnosis?
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 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 is failing and needs replacement.
The +12V rail is significantly below the ATX specification of ±5% (11.4V minimum), indicating a failing power supply. The other rails are within tolerance but the +12V is critical for CPU and GPU power. A failing PSU can cause random shutdowns as voltage drops under load. Replacement is necessary.
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 motherboard voltage regulator is failing.
Why it's wrong here
A failing VRM would typically cause instability on the CPU or memory, but the low +12V reading is measured at the PSU output, indicating the source is the PSU itself.
- ✓
The power supply is failing and needs replacement.
Why this is correct
A +12V reading of 11.2V is below the ATX tolerance of 11.4V, indicating the PSU cannot maintain proper voltage, likely due to aging capacitors or other internal faults.
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 system is drawing too much current, causing voltage drop.
Why it's wrong here
While excessive load can cause voltage drop, the PSU should still regulate within spec if it is functioning correctly; a healthy PSU would shut down or limit current before dropping this low.
- ✗
The AC input voltage is too low.
Why it's wrong here
Low AC input would affect all rails proportionally, but the +5V and +3.3V rails are within spec, so the issue is isolated to the +12V rail regulation.
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.
Trap categories for this question
Command / output trap
A failing VRM would typically cause instability on the CPU or memory, but the low +12V reading is measured at the PSU output, indicating the source is the PSU itself.
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 is failing and needs replacement. — The +12V rail is significantly below the ATX specification of ±5% (11.4V minimum), indicating a failing power supply. The other rails are within tolerance but the +12V is critical for CPU and GPU power. A failing PSU can cause random shutdowns as voltage drops under load. Replacement is necessary.
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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