220-1201 Hardware and Network Troubleshooting Practice Question
A technician is troubleshooting a desktop PC that intermittently powers off after 15–20 minutes of use, especially under heavy load. The power supply is a 500 W unit that came with the case. The system has a high-end GPU and an overclocked CPU. The technician has already confirmed the wall outlet and power cable are good. Which of the following is the MOST likely cause of the shutdowns?
⚠ Common exam trap
The trap here is assuming any shutdown under load is thermal, when power delivery instability can produce the same symptom without high temperatures.
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 power supply is undersized or failing, causing voltage rail sag under load.
The system powers off after sustained heavy load, which strongly suggests the power supply cannot deliver stable voltage to the high-end GPU and overclocked CPU. A 500 W unit is often insufficient for such a configuration, and aging components can worsen the issue. Replacing the PSU with a higher-capacity unit and testing under load is the correct troubleshooting path.
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 power supply is undersized or failing, causing voltage rail sag under load.
Why this is correct
Intermittent shutdowns under load with a high-end GPU and overclocked CPU point to inadequate or degrading PSU capacity. A 500 W unit may not supply stable +12 V rails when demand spikes, triggering protective shutdown. Replacing with a higher-wattage, quality PSU and verifying rail stability is the appropriate next step in this scenario.
- ✗
The RAM is mismatched, causing memory errors that crash the system.
Why it's wrong here
Mismatched RAM usually causes POST errors, blue screens, or application crashes, not clean power-offs under load. Memory faults do not typically trigger the system to power down completely. The described behavior—shutdown after sustained heavy load—is characteristic of power delivery problems rather than memory instability.
- ✗
The motherboard BIOS is outdated and does not support the GPU.
Why it's wrong here
An outdated BIOS may cause compatibility issues, but it would not typically cause intermittent shutdowns after 15–20 minutes of load. GPU incompatibility usually manifests as no video, POST errors, or instability at boot. The symptom pattern here is more consistent with a power supply that cannot sustain the load.
- ✗
The CPU cooler is loose, causing thermal throttling and automatic shutdown.
Why it's wrong here
A loose CPU cooler typically causes thermal throttling or an immediate thermal shutdown, often with a temperature warning. The symptom here is intermittent after 15–20 minutes under load, which is more consistent with power delivery instability than with a mounting issue. Thermal shutdowns usually occur much sooner and are accompanied by high temperature readings.
Go deeper
Related to this question
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Default Gateway Configuration
Key term
CPU
The Central Processing Unit (CPU) is the main electronic brain of a computer that carries out instructions from software by performing basic arithmetic, logic, control, and input/output operations.
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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