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220-1201 Practice Question: After replacing a motherboard, a technician finds…
After replacing a motherboard, a technician finds that the PC will not power on at all. The power supply fan does not spin, and no LEDs light up. The PSU was working before the replacement. 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 front panel power switch header is not connected correctly
No power at all after a motherboard swap strongly suggests an electrical connection issue. The most common cause is that the front panel power switch header is not connected correctly to the motherboard, or the PSU is not properly connected to the motherboard.
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 power supply is dead
Why it's wrong here
A dead power supply (PSU) would indeed prevent the system from powering on. However, since the PSU was presumably functional before the motherboard replacement, it is less probable that the PSU itself failed coincidentally during the swap. Technicians typically check all power connections first, as a disconnected or improperly seated main ATX power cable (24-pin) or CPU power cable (4/8-pin EPS) to the motherboard would present similar "no power" symptoms without the PSU being faulty.
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The CPU is not compatible with the new motherboard
Why it's wrong here
An incompatible CPU would prevent the system from completing the Power-On Self-Test (POST) and booting, often resulting in a blank screen or specific diagnostic lights/beep codes. However, the system would typically still receive power, indicated by fans (CPU, case, PSU) spinning up for a short period before shutting down or remaining on without display. The scenario describes no power at all, which is distinct from a system receiving power but failing to POST due to CPU incompatibility.
- ✓
The front panel power switch header is not connected correctly
Why this is correct
The front panel power switch header connects the physical power button on the computer case to the motherboard. When the power button is pressed, it momentarily completes a circuit on specific pins of this header, signaling the motherboard to initiate the power-on sequence for the power supply unit (PSU). If these small, often unlabeled, pins are incorrectly connected or not connected at all after a motherboard replacement, the electrical signal from the power button will not reach the motherboard, resulting in the system appearing completely dead with no fans or lights.
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The RAM is not seated properly
Why it's wrong here
If the RAM modules are not properly seated in their slots, the system will typically power on, meaning the power supply unit (PSU) will activate, and fans (CPU, case, PSU) will spin. However, the system will fail to complete the Power-On Self-Test (POST), often resulting in a blank screen, specific beep codes from the motherboard, or diagnostic LEDs indicating a memory issue. This is distinct from a scenario where the system exhibits no signs of power whatsoever, such as no fan movement or indicator lights.
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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.