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220-1201 Practice Question: A customer complains that their computer takes a…
A customer complains that their computer takes a very long time to boot and sometimes shows a 'CMOS Checksum Error' before starting. What is the most likely hardware issue?
⚠ Common exam trap
220-1201 often tests the misconception that a CMOS checksum error indicates firmware corruption or disk failure, when the overwhelmingly common cause is simply a depleted CMOS battery.
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 CMOS battery is depleted
The CMOS battery (a CR2032 coin cell on the motherboard) powers the RTC and the CMOS SRAM that stores BIOS/UEFI settings, including system time and hardware configuration. When it depletes, settings are lost on power-off, producing the 'CMOS Checksum Error' at POST and forcing the system to re-detect hardware and prompt for setup, which dramatically lengthens boot time. Replacing the battery and reconfiguring BIOS resolves both symptoms.
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 hard drive is failing
Why it's wrong here
Hard drive issues primarily relate to the storage and retrieval of data, not the system's fundamental configuration settings stored in CMOS. A failing hard drive typically manifests as slow performance, read/write errors, corrupted files, or a complete inability to boot into the operating system due to inaccessible boot sectors or OS files. It does not directly affect the integrity of the BIOS/UEFI settings or trigger a CMOS checksum error.
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The RAM module is faulty
Why it's wrong here
RAM (Random Access Memory) is volatile memory used for active data processing and temporary storage during system operation. Faulty RAM modules commonly lead to system instability, blue screens of death (BSODs), random reboots, application crashes, or specific POST (Power-On Self-Test) beep codes indicating memory issues. While critical for system operation, RAM problems do not directly corrupt the non-volatile CMOS settings or cause a checksum error related to the BIOS configuration.
- ✓
The CMOS battery is depleted
Why this is correct
The CMOS battery (often a CR2032 coin cell) provides continuous power to the Complementary Metal-Oxide-Semiconductor (CMOS) memory chip, which stores critical system configuration settings like date, time, boot order, and hardware parameters. When this battery is depleted, the CMOS memory loses power, causing these settings to revert to default or become corrupted. This frequently results in a "CMOS checksum error" message during boot, as the system detects an inconsistency in its stored configuration.
- ✗
The UEFI firmware is corrupted
Why it's wrong here
UEFI (Unified Extensible Firmware Interface) firmware is the low-level software that initializes hardware components and manages the boot process. If the UEFI firmware itself is corrupted, the system would likely fail to POST, display specific error codes related to firmware integrity, or become completely unbootable, often referred to as a "bricked" state. While a CMOS checksum error indicates an issue with the *settings* stored by the firmware, it does not imply corruption of the firmware *code* itself.
Visual reference
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Related to this question
Learn chapter
Default Gateway Configuration
Key term
Motherboard
The main circuit board inside a computer that connects all components so they can communicate with each other and receive power.
Key term
Unified Extensible Firmware Interface
UEFI is the modern replacement for BIOS that controls how a computer starts up and loads the operating system.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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.