Computer Shuts Down After 10 Seconds: Thermal Paste Application
A technician installs a new CPU and cooler in a desktop computer. After powering on, the system starts but shuts down abruptly after about 10 seconds. The technician has verified that the CPU cooler fan is spinning and the CPU is correctly seated in the socket. Which of the following should the technician check NEXT?
Quick Answer
The answer is to check the application of thermal paste between the CPU and cooler. This is correct because when a computer shuts down after 10 seconds following a CPU installation, the system is almost certainly triggering thermal overload protection, known as TjMax. Even if the cooler fan spins and the CPU is seated correctly, poor heat transfer from the CPU die to the cooler’s cold plate—caused by missing, uneven, or excessive thermal paste—will cause the processor to hit critical temperature almost instantly, forcing an emergency shutdown. On the CompTIA A+ Core 1 220-1101 exam, this scenario tests your understanding of thermal management and the importance of proper paste application; a common trap is assuming a spinning fan guarantees adequate cooling. Remember the mnemonic “Paste First, Panic Last”—always verify thermal paste before suspecting a faulty CPU or power supply.
⚠ Common exam trap
The trap here is that candidates see the CPU cooler fan spinning and assume cooling is adequate, overlooking that the fan spinning does not guarantee proper thermal interface material (TIM) contact between the CPU and the heatsink.
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 application of thermal paste between the CPU and cooler
The system shutting down after 10 seconds, despite the CPU cooler fan spinning and the CPU being seated correctly, strongly indicates thermal overload protection (TjMax) is being triggered. The most likely cause is insufficient or improperly applied thermal paste, which prevents effective heat transfer from the CPU die to the cooler's cold plate, causing the CPU to rapidly reach critical temperature and initiate an emergency shutdown.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Check the application of thermal paste between the CPU and cooler
Why this is correct
Insufficient thermal paste, or a poor bond from dried or contaminated compound, prevents heat transfer from the CPU die to the cooler's base. The fan spins, but the heatsink stays cool, so the processor hits its thermal trip point within seconds and the system shuts down abruptly. Reseating with fresh paste satisfies the stem's cooling constraint.
- ✗
Verify that the power supply voltage switch is set correctly for the local mains voltage
Why it's wrong here
A mains voltage switch mismatch typically prevents the PSU from starting at all, or causes immediate shutdown on the primary rail — not a consistent 10-second run. It is tempting because incorrect mains selection does damage hardware, but the correct check here is CPU thermal protection, since a seated cooler can still make poor contact.
- ✗
Replace the CMOS battery on the motherboard
Why it's wrong here
A depleted CMOS battery loses BIOS settings and clock time, but does not trigger a shutdown after ten seconds of normal operation. Replacing it is tempting because it is a cheap, common fix for boot anomalies, yet the actual cause is CPU overheating protection, which halts the system once the die exceeds its thermal threshold.
- ✗
Test the RAM modules in different slots
Why it's wrong here
Faulty RAM typically triggers POST beep codes, boot loops or blue screens rather than a consistent shutdown after roughly ten seconds with the fan confirmed spinning. Testing RAM is tempting as a general next step, and would be correct if the system failed to POST or reported memory errors.
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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 technician replaced the thermal paste on a desktop computer's CPU. After reassembling the system and powering it on, the computer runs for about 10 seconds and then shuts off. The technician touches the CPU heatsink and finds it is cool to the touch. The CPU fan is spinning. Which of the following is the MOST likely cause of the shutdown?
medium- A.The CPU fan is not spinning fast enough.
- ✓ B.The heatsink is not making proper contact with the CPU.
- C.The power supply unit is failing.
- D.The motherboard is shorted against the case.
Why B: The CPU thermal protection mechanism triggers a shutdown when the CPU temperature exceeds its safe operating threshold. Since the heatsink is cool to the touch, it indicates that heat is not being transferred from the CPU to the heatsink, which is a classic symptom of poor contact between the CPU and heatsink. Even though the CPU fan is spinning, without proper thermal transfer, the CPU rapidly overheats and shuts down to prevent damage.
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.