220-1101 Hardware Practice Question
A technician is assembling a new desktop computer with an AMD Ryzen 5 CPU on a B550 motherboard. After installing the CPU, heatsink, RAM, and graphics card, and connecting all power cables, the technician powers on the system. The case fans spin, the motherboard LEDs light up, but there is no display output and no beep codes. The motherboard has a set of diagnostic LEDs; the LED labeled 'CPU' remains lit. Which of the following should the technician check FIRST?
⚠ Common exam trap
Candidates often assume a spinning fan and lit LEDs mean the motherboard has full power, but the CPU requires a dedicated power cable that is separate from the main 24-pin ATX connector.
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
✓
Verify that the 8-pin CPU power cable is connected to the motherboard
The CPU diagnostic LED remaining lit indicates a problem with the CPU or its power delivery. The most common cause is the 8-pin EPS12V CPU power cable not being connected, which supplies dedicated 12V power to the processor. Without this cable, the CPU cannot initialize, even though case fans and motherboard LEDs receive power from the 24-pin ATX connector.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Reseat the RAM modules and try different slots
Why it's wrong here
Reseating RAM addresses memory initialization problems, which are typically indicated by a separate DRAM diagnostic LED or a repeating beep code. A CPU LED, by contrast, signals that the processor is not being detected or is not receiving power, and operating on memory modules will have no effect on the CPU power integrity. Even if the RAM were faulty, the motherboard would halt at a different POST stage before illuminating the CPU LED.
- ✓
Verify that the 8-pin CPU power cable is connected to the motherboard
Why this is correct
The 8-pin CPU power connector (often split into 4+4 pin EPS12V) delivers the 12V rail directly to the motherboard's voltage regulator modules, which supply the processor's Vcore. Without it, the CPU cannot power on, and the motherboard's error LED will light up during the POST phase. Always verify that both the 24-pin ATX and the 8-pin EPS connectors are fully seated, as a partially inserted cable is a common oversight on new builds.
- ✗
Reinstall the dedicated graphics card
Why it's wrong here
A dedicated graphics card failure usually results in a black screen or a lit VGA diagnostic LED, not a CPU LED, because the CPU itself may still be running normally. The CPU LED is tied to the processor's power-good signal or its initialization handshake with the chipset, which is independent of the PCIe slot and the GPU. Reinstalling the graphics card would only resolve an issue in the display output path, not a missing CPU power supply.
- ✗
Update the motherboard BIOS to support the CPU
Why it's wrong here
While a motherboard BIOS update might be necessary to recognize a newer Ryzen CPU, a BIOS incompatibility typically produces a blank display or a specific CPU status LED that may blink in a pattern, but it is far less common than a missing physical power connection. Moreover, the CPU LED on many boards lights up not only for an unsupported processor but also for a failure of the CPU's power delivery, which a BIOS flash cannot remedy. Because the build is brand-new, the first and most probable cause is an unseated or overlooked 8-pin CPU power cable, so BIOS flashing should be considered only after exhausting power-related checks.
Go deeper
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Key term
Dual In-line Memory Module
A Dual In-line Memory Module (DIMM) is a small circuit board that holds memory chips and plugs into a computer's motherboard to provide Random Access Memory (RAM).
Key term
Advanced Micro Devices
Advanced Micro Devices (AMD) is a company that designs and manufactures central processing units (CPUs), graphics processing units (GPUs), and other computer hardware components used in personal computers, servers, and embedded systems.
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Written by Johnson Ajibi, MSc IT Security
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This 220-1101 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 220-1101 exam.