220-1101 Hardware Practice Question
A technician is assembling a desktop computer using an Intel LGA1151 socket motherboard. The CPU has been installed correctly with thermal paste and a heatsink. When the power button is pressed, the system powers on for about three seconds, then shuts off, and then repeatedly attempts to restart. The CPU cooler fan spins normally during that time. Which of the following is the MOST likely cause?
⚠ Common exam trap
The trap here is that candidates see the CPU cooler fan spinning and assume the CPU is receiving power, but the fan is powered by a separate 12V rail (often from the main 24-pin ATX connector), while the CPU itself requires the dedicated EPS12V connector to function.
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 4+4 pin EPS12V power connector is not plugged into the motherboard
The 4+4 pin EPS12V connector provides dedicated power to the CPU. Without it, the CPU cannot initialize, causing the motherboard's fail-safe to power off after a few seconds and then repeatedly attempt to restart. The cooler fan spinning normally indicates the system is receiving basic power, but the CPU lacks the necessary voltage to complete POST.
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 4+4 pin EPS12V power connector is not plugged into the motherboard
Why this is correct
Without the EPS12V connector, the CPU VRM receives no 12-volt input, so the processor never powers up. The motherboard's startup sequence detects the missing CPU power via the power-good or fault circuit and forces a hard shutdown within seconds. This symptom is classic for a forgotten 4+4-pin cable because the rest of the board — fans, LEDs, ATX power — still energizes.
- ✗
The RAM modules are not fully seated in their slots
Why it's wrong here
Loose or improperly seated RAM typically causes the POST to halt before video initializes, producing a repeating beep code or illuminated LED, while the motherboard remains powered on. If the RAM is truly missing a pin contact, the memory controller never passes training, so you get a blank screen — not a start-and-immediate-shutdown cycle. This distinction is key, because a power-loss symptom after a brief startup points away from memory seating and toward a missing CPU power feed.
When this WOULD be correct
A technician builds a PC and upon pressing the power button, the system powers on but there is no display output, no beeps, and the fans spin continuously. The CPU cooler fan spins normally. In this case, improperly seated RAM would be the most likely cause.
- ✗
The CMOS battery is depleted
Why it's wrong here
The CMOS battery only backs up the real-time clock and volatile BIOS settings when the computer is fully unplugged, supplying roughly 3 volts to the CMOS RAM. As long as the power supply is plugged in, standby power from the 24-pin ATX connector maintains those settings, and a depleted battery causes no interruption to the boot sequence. A dead battery would require replacing, but it cannot make the system power off after a few seconds; symptoms are reset date/time or lost UEFI configurations.
- ✗
The power supply is not rated for the required wattage
Why it's wrong here
An under-rated power supply normally manifests as instability when the system draws high current, such as during gaming or stress testing, not as an immediate cutoff during the first second of POST. The idle power draw at startup is usually far below even a marginal PSU's rated capacity, so the PSU would still provide stable rails. If the power supply genuinely lacks sufficient wattage to boot, it would usually fail to turn on at all or trip OCP when the CPU fan and drives spin up, but the more consistent cause of a quick shutdown after power-on is the missing EPS cable.
When this WOULD be correct
A technician builds a PC with a high-end GPU and multiple drives. When running a stress test, the system randomly shuts down. The PSU is a 400W unit, but the estimated load is 450W. In this scenario, the PSU not being rated for the required wattage would be the most likely cause.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 220-1101 exam frequently reuses these exact scenarios with slightly different constraints.
✓The 4+4 pin EPS12V power connector is not plugged into the motherboardCorrect answer▾
Why this is correct
Without the EPS12V connector, the CPU VRM receives no 12-volt input, so the processor never powers up. The motherboard's startup sequence detects the missing CPU power via the power-good or fault circuit and forces a hard shutdown within seconds. This symptom is classic for a forgotten 4+4-pin cable because the rest of the board — fans, LEDs, ATX power — still energizes.
✗The RAM modules are not fully seated in their slotsWrong answer — click to see why▾
Why this is wrong here
In this scenario, the system powers on for a few seconds and then shuts off, which is typical of a power delivery issue like a missing EPS12V connector. RAM seating issues usually cause beep codes, no display, or failure to POST, not a power-on-then-shutdown cycle.
★ When this WOULD be the correct answer
A technician builds a PC and upon pressing the power button, the system powers on but there is no display output, no beeps, and the fans spin continuously. The CPU cooler fan spins normally. In this case, improperly seated RAM would be the most likely cause.
Why candidates choose this
Candidates may associate any boot failure with RAM issues because RAM is a common source of problems, and they might overlook the distinct symptom of a repeated power cycle indicating a power supply connection problem.
✗The power supply is not rated for the required wattageWrong answer — click to see why▾
Why this is wrong here
The system powers on briefly and then shuts off, which is a classic sign of a missing EPS12V CPU power connector, not insufficient PSU wattage. A PSU with insufficient wattage would typically cause instability under load or failure to boot, not a precise 3-second power cycle.
★ When this WOULD be the correct answer
A technician builds a PC with a high-end GPU and multiple drives. When running a stress test, the system randomly shuts down. The PSU is a 400W unit, but the estimated load is 450W. In this scenario, the PSU not being rated for the required wattage would be the most likely cause.
Why candidates choose this
Candidates may assume that any power-related issue is due to insufficient wattage, especially if they have encountered systems that fail to boot or shut down under load due to an underpowered PSU.
Analysis generated from the official 220-1101blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.