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PC FIX
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.

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?

  • Changing CPU does not boot
  • New CPU screen does not appear
  • CPU LED on

main causes

  • BIOS not supported
  • CPU auxiliary power/installation problem
  • Motherboard Compatibility

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

Disconnect all USB and external devices and reboot

External storage or USB devices may be interfering with the POST or boot sequence.

Difficulty Easy time 3-5 minutes cost 0 won
  1. 1Turn off your PC completely.
  2. 2Disconnect USB memory, external hard drive, printer, and docking device.
  3. 3Turn it back on, leaving only the keyboard and monitor.

confirmation point

After these steps, see if the “Change CPU and won’t boot” symptom decreases or disappears. If there is no change, check the possibility of BIOS unsupport in the next step.

2

Check BIOS and boot order

Determine if it is a POST or Windows phase issue and check for incorrect boot order.

Difficulty Moderate time 5 to 15 minutes cost 0 won
  1. 1Enter BIOS/UEFI.
  2. 2Check whether the CPU, RAM, and system drive are displayed normally.
  3. 3Verify that Windows Boot Manager is in the correct boot order.
  4. 4Rather than arbitrarily changing UEFI/Legacy settings, check that they match your existing installation method.
3

Run Windows Startup Repair

System file/BCD/boot record problems can be automatically fixed with Startup Repair.

Difficulty Moderate time 10~30 minutes cost 0 won
  1. 1Enter the Windows Recovery Environment (WinRE).
  2. 2Select Troubleshoot → Advanced Options → Startup Repair.
  3. 3After completion, check if it boots normally.
4

Check the same symptom in safe mode

Safe mode loads only a minimal number of drivers and services, which is helpful in narrowing down the cause.

Difficulty Moderate time 10-20 minutes cost 0 won
  1. 1Go to Settings → System → Recovery → Advanced startup.
  2. 2After restarting, select Troubleshoot → Advanced options → Startup Settings → Restart.
  3. 3See if the issue reproduces in safe mode.

confirmation point

In safe mode, if normal, third-party drivers, services, and startup programs are suspected first.

5

Revert recent changes

If the problem started immediately after installing an update, driver, or new program, a recent change may be the cause.

Difficulty Moderate time 10~30 minutes cost 0 won
  1. 1Find out when the problem first started.
  2. 2If there are any programs, drivers, or updates that were installed just before, uninstall or roll them back one by one.
  3. 3Reboot every time you make a change and check for symptoms.
6

Diagnosing RAM and system drives

If repeated recovery fails, you should check for possible memory or storage errors.

Difficulty Advanced time 30~90 minutes cost 0 won
  1. 1Check the memory and storage device using the manufacturer's hardware diagnosis.
  2. 2If there are SMART warnings or memory errors, back up important data first.
  3. 3Parts found to be faulty will be considered for replacement.

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.

Boot

Motherboard CPU, DRAM, VGA or BOOT debug LED stays lit

When solving problems where the motherboard CPU, DRAM, VGA, and BOOT LEDs keep turning on, it is important to rule out the causes one at a time. Based on the “CPU LED on” symptom, check whether the component initialization failed, power supply or installation is defective, and then proceed to the next step. Distinguish between the POST stage and the Windows startup stage, then check in that order: external device, boot settings, and recovery environment.

View solutions →
Boot

The computer turns on but does not boot into Windows.

Among boot problems, the “powers on but does not boot” symptom may be related to boot file corruption or storage device issues. Distinguish between the POST stage and the Windows startup stage, then check in that order: external device, boot settings, and recovery environment.

View solutions →
Boot

Problem with beep sound and no screen when booting

If the “boot beep sound” repeats, it is better to narrow it down to memory or graphics card recognition failure or motherboard POST diagnostic error rather than changing several settings at once. Distinguish between the POST stage and the Windows startup stage, then check in that order: external device, boot settings, and recovery environment.

View solutions →
Boot

Suddenly asking for BitLocker recovery key

If you see the “bitlocker recovery key” symptom, candidate causes include TPM, BIOS, secure boot status changes, firmware updates, etc. 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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