20+ practice questions focused on Power Supply — one of the most tested topics on the CompTIA A+ Core 1 220-1201 exam. Each question includes a detailed explanation so you learn why the right answer is correct.
Start Power Supply PracticeA technician is troubleshooting a PC that emits a high-pitched whining noise under load. The noise is coming from the power supply area. The system is stable and temperatures are normal. What is the most likely cause?
Explanation: Coil whine is a common phenomenon in power supplies and other components when electrical current passes through inductors, causing them to vibrate at audible frequencies. It is typically harmless and does not indicate a defect, though it can be annoying. If the system is stable, no replacement is needed.
A technician is selecting a power supply for a workstation that will run 24/7 in a dusty environment. The PSU will be installed in a case with limited airflow. Which PSU feature is most important to prioritize for long-term reliability in this scenario?
Explanation: In dusty environments with limited airflow, a PSU with a high-quality, sealed bearing fan (e.g., fluid dynamic bearing) and a dust-resistant design (e.g., honeycomb grill, dust filters) is critical. Additionally, a higher efficiency rating (e.g., 80 Plus Gold or better) reduces heat output, easing thermal stress. The most important single feature is the fan's reliability and the PSU's ability to handle particulate ingress.
A technician is replacing a power supply in an office desktop. The new PSU has a 24-pin main connector, but the motherboard has a 20-pin socket. What should the technician do?
Explanation: Modern ATX power supplies often have a 24-pin connector that is backward compatible with 20-pin motherboards; the extra 4 pins can be slid or snapped off. This allows the PSU to work without modification. Forcing the 24-pin into a 20-pin socket could damage the board.
A technician is troubleshooting a PC that shuts down randomly after a few minutes of use. The technician measures the +12V rail with a multimeter and gets 11.2V. The +5V rail reads 4.9V, and the +3.3V rail reads 3.2V. What is the most likely diagnosis?
Explanation: The +12V rail is significantly below the ATX specification of ±5% (11.4V minimum), indicating a failing power supply. The other rails are within tolerance but the +12V is critical for CPU and GPU power. A failing PSU can cause random shutdowns as voltage drops under load. Replacement is necessary.
A technician is upgrading a server's power supply to support additional drives. The current PSU is a 750W unit with a single +12V rail rated at 62A. The new drives will add 5A to the +12V load. The total calculated +12V load is 58A. Is the current PSU adequate?
Explanation: The PSU's +12V rail is rated for 62A, and the total load after adding drives is 58A, which is within the rating. However, it is good practice to leave headroom (typically 10-20%) to avoid running the PSU at maximum capacity, which can reduce efficiency and lifespan. In this case, the PSU is technically adequate but marginal.
+15 more Power Supply questions available
Practice all Power Supply questions1. Baseline your knowledge
Start with 10 questions to gauge your current understanding of Power Supply. This tells you whether you need a concept refresher or just practice.
2. Review every explanation
For each question — right or wrong — read the full explanation. Understanding why an answer is correct is more valuable than knowing the answer itself.
3. Focus on exam traps
Power Supply questions on the 220-1201 frequently use trap wording. Look for subtle differences in answers that test your precision, not just general knowledge.
4. Reach 80% consistently
Do repeated sessions until you score 80%+ three times in a row. Then move to mixed-mode practice to test cross-topic recall under realistic conditions.
The exact number varies per candidate. Power Supply is tested as part of the CompTIA A+ Core 1 220-1201 blueprint. Practicing with targeted Power Supply questions ensures you can handle any format or difficulty that appears.
Yes. Courseiva provides free 220-1201 practice questions across all exam topics and domains. The platform includes topic-based practice, mock exams, missed-question review, bookmarked questions, and readiness tracking — no account required.
Difficulty is subjective, but Power Supply is a high-priority exam concept tested in multiple ways — direct recall, scenario analysis, and command-output interpretation. Consistent practice is the best way to build confidence.
Launch a full Power Supply practice session with instant scoring and detailed explanations.
Start Power Supply Practice →