The answer is a failing hard drive. When a PC is running very slowly and the hard drive activity LED is constantly lit even while idle, with Task Manager showing 100% disk usage but no corresponding spike in CPU or memory usage, this points directly to physical drive failure rather than a software bottleneck. The constant LED and maxed-out disk queue indicate the drive is struggling to read or write data due to bad sectors or mechanical wear, forcing the system to repeatedly retry operations. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your ability to distinguish hardware failure from malware or fragmentation—a common trap is to blame high CPU or RAM, but here the disk is the sole bottleneck. Remember the mnemonic: “LED always on, disk is gone.”
220-1101 Core PC Hardware Troubleshooting Practice Question
This 220-1201 practice question tests your understanding of core pc hardware troubleshooting. 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's PC is running very slowly, and the hard drive activity LED is constantly lit even when idle. Task Manager shows 100% disk usage. Which component is most likely failing?
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.
Why wrong: Low RAM would cause high memory usage and paging to disk, but the symptom here is persistent 100% disk activity even when idle, not high memory usage.
B
Failing hard drive
A failing drive retries failing sectors, causing constant activity and high usage. Running a diagnostic tool like CHKDSK or S.M.A.R.T. test can confirm.
C
CPU overheating
Why wrong: CPU overheating causes throttling and slowness, but not specifically constant disk activity at 100%.
D
Malware infection
Why wrong: Malware can cause high disk usage, but the constant LED and 100% usage even at idle, combined with slowness, more strongly suggests hardware failure.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Failing hard drive
Constant 100% disk usage with no corresponding high CPU or memory usage is a classic sign of a failing hard drive, often due to bad sectors or mechanical wear. While a slow drive can be caused by malware or fragmentation, hardware failure is the primary suspect in this scenario.
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.
✗
Insufficient RAM
Why it's wrong here
Low RAM would cause high memory usage and paging to disk, but the symptom here is persistent 100% disk activity even when idle, not high memory usage.
✓
Failing hard drive
Why this is correct
A failing drive retries failing sectors, causing constant activity and high usage. Running a diagnostic tool like CHKDSK or S.M.A.R.T. test can confirm.
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.
✗
CPU overheating
Why it's wrong here
CPU overheating causes throttling and slowness, but not specifically constant disk activity at 100%.
✗
Malware infection
Why it's wrong here
Malware can cause high disk usage, but the constant LED and 100% usage even at idle, combined with slowness, more strongly suggests hardware failure.
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.
Core PC Hardware Troubleshooting — This question tests Core PC Hardware Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Failing hard drive — Constant 100% disk usage with no corresponding high CPU or memory usage is a classic sign of a failing hard drive, often due to bad sectors or mechanical wear. While a slow drive can be caused by malware or fragmentation, hardware failure is the primary suspect in this scenario.
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.
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