P
PC FIX
Power

Computer turns on and then immediately turns off

If the current symptom is close to “turns off as soon as power is turned on,” first check for POST stage hardware errors, CPU auxiliary power, or RAM installation problems. It is easy to find the cause of sudden shutdown or reboot by checking the power supply, temperature, and tuning settings separately.

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?

  • Turns off as soon as power is turned on
  • Turns off after a few seconds
  • The fan starts spinning and immediately stops

main causes

  • POST phase hardware failure
  • CPU auxiliary power or RAM installation problems
  • Power supply protection circuit operation

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

Check the power cable and power strip

Poor contact or overloaded power strips can cause a momentary power outage.

Difficulty Easy time 5 minutes cost 0 won
  1. 1Reconnect the power cable of the PC and the outlet.
  2. 2If possible, test on a different wall outlet or working power strip.
  3. 3The laptop uses a rated charger.

confirmation point

After these steps, see if the “turns off as soon as you turn it on” symptom decreases or disappears. If there is no change, check for possible POST stage hardware errors in the next step.

2

Check CPU and GPU temperatures

If overheating occurs, the system may shut down or reboot for protection.

Difficulty Easy time 10-20 minutes cost 0 won
  1. 1If the issue reproduces, check the CPU/GPU temperature.
  2. 2Make sure the vents are not blocked.
  3. 3If the temperature is abnormally high, stop high-load operations and solve cooling problems first.
3

Revert overclock, undervolt, and XMP/EXPO to default

Limit settings may cause reboots when the load increases, even if they are normally normal.

Difficulty Moderate time 10-20 minutes cost 0 won
  1. 1Disable CPU/GPU overclocking and undervolting.
  2. 2Temporarily turn off memory XMP/EXPO for diagnostic purposes.
  3. 3Repeat the same operation in the default state.
4

Check blue screen or event log

Even if it looks like a power issue, it may actually be an automatic reboot after a driver/hardware error.

Difficulty Moderate time 10-20 minutes cost 0 won
  1. 1If you see a blue screen stop code, write it down.
  2. 2Check the system log in Event Viewer for errors just before rebooting.
  3. 3If the same error repeats, check the corresponding device first.
5

Checking the power supply, battery, and power supply

If it turns off or reboots only under high load, there is a possibility of reduced power delivery.

Difficulty Advanced time 30 minutes or more cost Possible occurrence when replacing parts
  1. 1Check the GPU auxiliary power and motherboard power connections.
  2. 2If possible, cross test with a good power supply.
  3. 3The laptop will check the battery diagnostics and whether the adapter is rated.

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.

Power

Computer suddenly turns off

If the current symptom is close to “the computer suddenly turns off,” first check for overheating protection and power supply output instability. It is easy to find the cause of sudden shutdown or reboot by checking the power supply, temperature, and tuning settings separately.

View solutions →
Power

Problem with the computer turning on and off repeatedly

This guide is organized to categorize items such as failed memory initialization, overclocking, or unstable BIOS settings in a safe order for “infinite reboot” situations. It is easy to find the cause of sudden shutdown or reboot by checking the power supply, temperature, and tuning settings separately.

View solutions →
Power

Computer suddenly reboots while in use

Among power issues, the “computer reboots alone” symptom may be related to power instability or overheating. It is easy to find the cause of sudden shutdown or reboot by checking the power supply, temperature, and tuning settings separately.

View solutions →
Power

Laptop not turning on at all

If you are experiencing the “Laptop not turning on” symptom, possible causes include charger or adapter issues, or a deep battery discharge. Classify the charger, battery, and power management circuits in order, starting with the easiest items.

View solutions →

Look for other symptoms too

If you enter the symptoms you are currently seeing in the PC FIX search box, we will find the related problem.

Search for other issues →