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220-1201 Practice Question: That their computer will not boot and the…
A user reports that their computer will not boot and the motherboard's diagnostic LEDs show a CPU error. You reseat the CPU and check for bent pins, but the error persists. Which of the following should you check next?
⚠ Common exam trap
220-1201 often tests the assumption that a CPU error LED always means a faulty or misseated CPU, when in fact power delivery (the EPS/ATX12V connector) is the more common culprit and should be verified first.
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 CPU power cable is not fully connected
A CPU error LED that persists after reseating the CPU and checking for bent pins strongly suggests the CPU is not receiving power. The 4-pin or 8-pin EPS/ATX12V CPU power connector on the motherboard must be firmly seated; if it is loose or missing, the CPU will not initialize and the board will flag a CPU fault. This is a common oversight during builds or after moving a system.
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 RAM modules are in the correct slots
Why it's wrong here
While incorrect RAM installation or faulty modules can prevent a system from booting, modern motherboards are designed to diagnose these issues specifically. A RAM error would typically illuminate a dedicated RAM diagnostic LED (often labeled "DRAM" or "MEM") on the motherboard, or produce a specific POST beep code indicating a memory problem. It would not directly trigger a CPU error LED, as the CPU itself is likely receiving power and attempting to initialize, but failing to find usable memory.
- ✗
The motherboard's BIOS is corrupted
Why it's wrong here
A corrupted BIOS (Basic Input/Output System) can indeed prevent a computer from booting, as the BIOS contains the essential instructions for initial hardware initialization and POST. However, a BIOS corruption typically manifests as no display output, continuous reboots, or a general system fault LED, rather than a specific CPU error LED. The CPU itself would likely be powered and attempting to execute the corrupted BIOS instructions, not necessarily indicating a CPU power or functionality issue.
- ✓
The CPU power cable is not fully connected
Why this is correct
The CPU requires a dedicated power connection, typically an 8-pin (or 4+4 pin) EPS connector, separate from the main 24-pin ATX power connector. If this CPU power cable is loose, partially connected, or completely disconnected, the CPU will not receive the necessary voltage to operate. Motherboards are designed to detect this lack of power to the processor and will illuminate the CPU diagnostic LED, indicating a critical power delivery failure to the central processing unit, thus preventing any boot sequence.
- ✗
The CPU cooler is installed incorrectly
Why it's wrong here
An incorrectly installed CPU cooler, or one with insufficient thermal paste, would primarily lead to rapid CPU overheating under load. While this can cause the system to shut down abruptly to prevent damage, it would not typically prevent the initial Power-On Self-Test (POST) from completing or trigger a CPU error LED at boot. The CPU would still receive power and attempt to initialize; the error would manifest later as thermal throttling or an immediate shutdown after a brief period of operation, not as an initial CPU power or functionality fault.
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The Central Processing Unit (CPU) is the main electronic brain of a computer that carries out instructions from software by performing basic arithmetic, logic, control, and input/output operations.
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JA
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.