P
PC FIX
CPU

CPU usage remains at 100%

This guide is designed to classify specific process overload and malware items in a safe order in the “CPU 100%” situation. Check process load, power mode, temperature and clock together to distinguish between software load and hardware limitations.

Solving Order
We've organized the methods starting with the simplest and least expensive ones. Please check the solutions one by one, starting from the top.

Do you have these symptoms?

  • CPU 100%
  • Processor utilization 100
  • Computer fan is noisy and slow

main causes

  • Specific process overload
  • malware
  • background update

How to solve

Please check them in order from the top. If the issue is resolved, you do not need to proceed to the next step.

1

Find processes using a lot of CPU in Task Manager

First, determine whether it is a software load or a problem with the CPU itself.

Difficulty Easy time 5-10 minutes cost 0 won
  1. 1Open Task Manager and sort by CPU column.
  2. 2Log the parent process when symptoms occur.
  3. 3Check if the update/encoding/game load is normal for the app.

confirmation point

After these steps, see if the “CPU 100%” symptom decreases or disappears. If there is no change, the possibility of specific process overload is also checked in the next step.

2

Check power mode and CPU clock

CPU performance may be limited due to power saving policy or manufacturer profile.

Difficulty Easy time 5-10 minutes cost 0 won
  1. 1Check the power mode in Settings → System → Power & Battery.
  2. 2Laptops are compared even when the charger is connected.
  3. 3Check if your CPU clock is stuck abnormally low.
3

Check CPU temperature and cooling status

Overheating may cause the CPU to automatically reduce clock speeds or cause the system to shut down.

Difficulty Moderate time 15-30 minutes cost 0 won
  1. 1Check CPU temperature during load.
  2. 2Check if the cooler fan and vents are normal.
  3. 3If the temperature is high, check the dust, cooler installation, and thermal condition.
4

Return overclock/undervolt to default

CPU settings instability can cause WHEA, reboots, and performance limitations.

Difficulty Moderate time 10-20 minutes cost 0 won
  1. 1Disable overclocking in BIOS and tuning program.
  2. 2Undervolts are also temporarily returned to their original values.
  3. 3Check whether it can be reproduced in the default state.
5

Request hardware inspection or repair

If the same remains after checking the software, you should check whether the part itself may be defective.

Difficulty Advanced time 30 minutes or more cost Possible occurrence during inspection/repair
  1. 1If possible, run manufacturer hardware diagnostics.
  2. 2During the warranty period, official service inspection takes priority over arbitrary disassembly.
  3. 3Back up important files before repair.

Frequently Asked Questions

We've put together a list of things we frequently check regarding this issue.

Related issues

If the symptoms do not match exactly, please check the issue below.

Performance

CPU utilization continues to be close to 100%

When troubleshooting CPU utilization that consistently approaches 100%, it is important to rule out causes one at a time. Based on the “CPU 100 percent” symptom, check for specific process overload and background updates and then proceed to the next step. Check process load, power mode, temperature and clock together to distinguish between software load and hardware limitations.

View solutions →
CPU

CPU clock is fixed low and performance is not good

If your current symptoms are closer to “low CPU clock”, first check for overheating or power throttling or power modes. Check process load, power mode, temperature and clock together to distinguish between software load and hardware limitations.

View solutions →
CPU

Problem with CPU temperature being too high

When troubleshooting a CPU temperature that is too high, it is important to rule out causes one at a time. Based on the “CPU temperature high” symptom, check the cooler installation, fan problem, dust/thermal condition, and then proceed to the next step. Temporarily reduce high loads, check the temperature, fan, and ventilation conditions, and then check the cooling system and power settings.

View solutions →
CPU

Computer not booting after CPU replacement

If the current symptom is close to “No booting after changing CPU,” first check for BIOS unsupport and CPU auxiliary power/installation problems. Distinguish between the POST stage and the Windows startup stage, then check in that order: external device, boot settings, and recovery environment.

View solutions →

Look for other symptoms too

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