Random Reboot Under CPU Load: Check CPU Voltage in BIOS
A technician is troubleshooting a desktop computer that randomly reboots under heavy CPU load. The technician has verified the CPU cooler is properly seated with thermal paste, run memory diagnostics (no errors), replaced the power supply, and updated all drivers. Running a CPU stress test causes the system to reboot after approximately 10 minutes. Which of the following should the technician check NEXT?
Quick Answer
The answer is to check the CPU voltage settings in BIOS. This is correct because when a system experiences a random reboot under CPU load stress test after all other common causes—like overheating, faulty RAM, a bad power supply, and driver issues—have been ruled out, the most likely culprit is an unstable vCore voltage. Under heavy load, a CPU demands consistent power; if the BIOS is set to an incorrect or insufficient voltage, the processor can crash or trigger a thermal protection reboot after a few minutes of sustained stress. On the CompTIA A+ Core 1 220-1101 exam, this scenario tests your ability to isolate voltage instability as a root cause, often disguised by the fact that the system runs fine at idle. A common trap is to suspect the CPU itself or the motherboard, but the consistent 10-minute reboot window points directly to BIOS voltage settings. Remember the mnemonic: “Voltage first, CPU last” when the cooler, RAM, and PSU have passed.
⚠ Common exam trap
The trap here is that candidates often jump to replacing the CPU or motherboard because the symptom appears to be a hardware failure, but the consistent 10-minute reboot under load is a classic sign of voltage instability, not a dead component.
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
✓
Check the CPU voltage settings in BIOS
The technician has already ruled out overheating (cooler seated with paste), memory errors, power supply issues, and driver conflicts. Under heavy CPU load, the system reboots after a consistent 10 minutes, which strongly suggests the CPU is not receiving stable voltage under load. Checking and adjusting the CPU voltage settings in BIOS is the next logical step because incorrect or insufficient vCore can cause the CPU to crash or trigger a thermal/voltage protection reboot when the CPU draws high current during a stress test.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Replace the CPU
Why it's wrong here
Replacing the CPU is a costly and time-consuming step that should only be done after all other causes are ruled out. There is no evidence yet that the CPU itself is defective.
- ✓
Check the CPU voltage settings in BIOS
Why this is correct
With cooling, memory, power supply and drivers eliminated, excessive CPU core voltage in BIOS is the remaining likely trigger. Overvolting raises heat and instability under sustained load, causing the reboots observed after roughly ten minutes of stress testing.
- ✗
Update the motherboard BIOS
Why it's wrong here
A BIOS update addresses firmware bugs and microcode errata, but the stem already isolates load-dependent reboots after cooler, RAM, PSU and driver checks. It is tempting because outdated firmware can cause instability, and updating would be right for known CPU errata or compatibility fixes — not for a thermal-throttling shutdown pattern.
- ✗
Replace the motherboard
Why it's wrong here
Motherboard replacement is invasive and unjustified before checking CPU temperature readings during the stress test, since the ten-minute reboot pattern indicates thermal shutdown. It is tempting because VRM or chipset faults can cause load-related resets, and would be correct once thermal and power causes are excluded.
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Same concept, more angles
1 more way this is tested on 220-1101
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A user reports that their desktop computer randomly restarts during gaming sessions. The technician has replaced the power supply unit (PSU) with a known-good unit of higher wattage, verified that CPU and GPU temperatures remain within normal limits during gaming, and updated all drivers. The RAM passes a memory test. Which of the following should the technician check NEXT?
medium- A.Replace the motherboard.
- ✓ B.Check the wall outlet voltage with a multimeter.
- C.Disable automatic restart in Windows System Properties.
- D.Run a stress test on the GPU.
Why B: The technician has already ruled out the PSU, overheating, driver issues, and faulty RAM. Random restarts under load can be caused by unstable or insufficient AC power from the wall outlet. Using a multimeter to check the wall outlet voltage is the logical next step to identify if the issue is upstream of the PSU, such as a sagging voltage or a loose neutral connection.
JA
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.