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220-1201 Practice Question: That their computer suddenly cannot find the boot…
A user reports that their computer suddenly cannot find the boot device, and the BIOS shows the SATA mode is set to 'IDE' instead of 'AHCI'. The drive was previously working. What is the most likely cause?
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 SATA mode was changed to IDE
If the SATA mode is changed from AHCI to IDE, the OS driver may not load, causing a boot failure. This can happen after a CMOS reset or accidental BIOS change. The question tests understanding of SATA controller modes and their impact on booting.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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The hard drive has failed
Why it's wrong here
A complete hard drive failure typically results in the drive not being detected by the BIOS at all, or it may exhibit distinct physical symptoms like clicking or grinding noises. While this would certainly prevent booting, the specific error "cannot find" often points to a detection issue rather than a complete physical failure, which might be accompanied by different error messages or no detection whatsoever.
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The SATA cable is loose
Why it's wrong here
A loose or faulty SATA data cable would most likely cause intermittent detection issues, where the drive might appear on some boots and disappear on others, or fail to be recognized sporadically. This scenario is less consistent with a sudden, persistent "cannot find" error that implies a fundamental change in how the system attempts to access the drive, rather than a simple physical connection problem.
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The CMOS battery is failing
Why it's wrong here
A failing CMOS battery primarily causes the BIOS settings to revert to their default configuration upon system restart, as it can no longer maintain power to the CMOS memory. While this default reset *could* change the SATA controller mode, the battery itself is an indirect cause; the direct reason for the boot failure is the subsequent mismatch between the OS's expected SATA mode and the new BIOS setting.
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The SATA mode was changed to IDE
Why this is correct
When Windows is installed with the SATA controller configured in AHCI mode, it installs specific AHCI drivers to communicate with the storage device. If the BIOS SATA mode is subsequently changed to IDE (or Legacy) mode, the operating system's existing AHCI drivers will be incompatible with the controller's new operational state. This driver mismatch prevents the OS from accessing the boot drive, leading directly to a "boot device not found" error, even if the drive is physically healthy.
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Related to this question
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Mobile Device Types and Features
Key term
SATA
SATA (Serial ATA) is an interface standard used to connect storage devices like hard drives and solid-state drives to a computer's motherboard.
Key term
Serial Advanced Technology Attachment
Serial Advanced Technology Attachment (SATA) is a computer bus interface used to connect storage devices like hard drives and solid-state drives to a computer's motherboard.
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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.