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How to Fix a CPU Not Detected or Fail (STEPS)

Why is my CPU not detected?

Your CPU may not be detected because of its incompatibility with the motherboard, wrong BIOS settings, a dead CPU, or loosely connected CPU power connectors in the slots.

  • CPU incompatibility
  • BIOS Settings
  • Dead CPU
  • Loose CPU power connectors
  • PCI-e not connected to GPU
  • CPU fans not working


CPU incompatibility

If your CPU is incompatible with the system requirements, then it will not be detected by the system. The only way to fix it is to replace the CPU with a compatible one. You can check the compatibility of the CPU by referring to the official website of your system manufacturer.


BIOS Settings

The BIOS settings, when changed from the default optimized settings, can lead to the CPU not getting detected by the system. You can fix this by entering the BIOS setup and changing the setting back to the “Optimized Default” setting.


Dead CPU

A dead CPU will not be detected by the system. You can spot a dead CPU issue by looking for symptoms like the computer turning ON but immediately turning OFF again.


Loose CPU power connectors

When the power connectors of the CPU are loosely attached or connected incorrectly, the CPU doesn’t get detected by the system. You can solve this issue by ensuring that the connectors are firmly and correctly connected.


PCI-e not connected to GPU

If you are using a GPU, make sure that it’s connected to the PCI-e connector and its settings are enabled in the BIOS setup. If not done, this will lead to the CPU not being detected in the system.


CPU fans not working or at wrong speeds

If the various CPU fans are set to different speed values, the CPU won’t be detected by the system. This can be changed by entering the BIOS screen and changing the different fan speed values to “Ignored” or “Not Applicable”.


What does the solid debug light (CPU not detected or fail) mean?

The solid debug light means that the CPU is not oriented correctly and it’s not fully locked in the computer system. The lever needs to hook under the slot to ensure proper connection set up between the CPU and other components of the computer.


CPU not detected or fail


What are the signs of a dead CPU?

The signs of a dead CPU may be identified by a computer which turns ON but there are no beeps or display on the screen.

A dead CPU can cause the computer to turn ON while the fans run at the high speed, the computer turns ON but immediately goes OFF, or the screen freezing.

  • The computer turns ON, no screen or beep
  • The computer turns ON, fans run at highest speed
  • The computer turns ON and goes OFF immediately
  • Screen freezes after a few minutes of turning ON
  • System halt errors


My motherboard is not detecting my CPU

If your motherboard is not detecting the CPU, it is because your CPU isn’t compatible with the motherboard, the power connectors are not firmly plugged in or the PCI-e connector is not connected to the GPU.

You can fix these issues by trying the solutions given below:

  1. Reset the CMOS by first powering OFF the computer. Open the system to expose the motherboard. Change the CMOS jumper from the 1-2 position to the 2-3 position. Wait for five minutes before changing it back to the original position, that is, 1-2 position. Restart the computer.
  2. Double-check the CPU power connectors if they are properly fitted to the slots.
  3. If you are using a GPU, then make sure that the PCI-e connector is connected to the graphics card of your computer.
  4. Go to the BIOS setting and change it to the “Optimized Default” setting. Save the changes and exit the setup.
  5. Shut down your computer and restart to see if the problem persists. This will most likely fix the issue of the motherboard not detecting the CPU.


CPU fan working but not detected

The CPU fan may be working but not detected because of the wrong fan settings in the BIOS setup of your computer.

You can fix this issue by following the steps given below.

  1. Restart your computer. Press the “F2”, “F12” or “Del” key to enter setup. Press the key as soon as the logo of your manufacturer appears on the screen.
  2. When you enter the BIOS screen, click the “Power” tab and go to the “Hardware Monitor Option” from the list that pops up on the screen.
  3. Select the “CPU fan speed” option and set it to “Ignored”.
  4. Select the “Chassis Fan Speed” option and set it to “N/A”.
  5. Select the “Power Fan Speed” option and set it to “Ignored”.
  6. This will eliminate the error of the CPU fan working but not being detected.


How to Fix a New build CPU not detected

The new build CPU may not be detected because of the motherboard turning the sounds OFF or the input-output shields shorting out of the motherboard.

Follow the troubleshooting methods given below to fix the issue of the new build CPU not being detected.

  1. Remove the GPU and one RAM stick.
  2. Remove the 8-pin CPU power plug and plug it back firmly.
  3. Connect the motherboard sitting on the top of the standoffs. This is necessary because the motherboard turns OFF the sound.
  4. Check the input-output shield to prevent it from shorting out of the motherboard.


Ryzen 7 CPU not detected

Ryzen 7 CPU may not be detected because of a loose 8-pin cable. You can fix this by removing the cable and putting it back firmly.

If the problem persists, you can try troubleshooting methods like resetting the CMOS by following the steps given below.

  1. Remove the main power supply of your computer and press the power button for thirty seconds.
  2. Short the CLR CMOS jumper by touching a flathead screwdriver for at least fifteen seconds.
  3. Connect the main power supply again to power up the computer.
  4. Press the power button of the computer.
  5. Tap the “Del” key repeatedly. Don’t keep pressing it. A screen asking you to press the “F1” key will come up.
  6. Press the “F1” key.
  7. Set the “Optimized Default” setting and press the “OK” button located in the “Exit” tab.
  8. Save the settings and exit the BIOS setup. This will fix the issue of the Ryzen 7 CPU not being detected.


MSI MPG Z490 CPU not detected

When the MSI MPG Z490 CPU is not detected, it may be due to an incompatible CPU, the distorted position of the power connector, BIOS problem or the EZ Debug light flashing.

You will need to fix this because the display of the monitor won’t come up.

Follow the steps given below to solve the issue of MSI MPG Z490 CPU not being detected.

  1. To check whether your CPU is compatible with the motherboard of your computer, go to MSI.com to check the compatibility report.
  2. Type the model of your CPU in the search bar located in the top right corner of the website. Press “Enter” to find the matches.
  3. Select the “Compatibility” tab under the name of the model. Go to the “CPU” tab to find the names of compatible models of CPU. If your CPU model is not given in the list of compatible models, then you will need to replace it with the compatible model.
  4. If your CPU model passes the compatibility test, move on to check the position of the CPU power connector. It should be firmly attached for the CPU to be detected.
  5. Remove the external components such as USB devices, USB flash drives, hard drives, PCI-e cards, and so on from the motherboard. Restart the computer. If it powers ON and the display comes, then the problem is in the external devices.


Disconnect the main power supply of your computer. Change the JBAT1 jumper from its original position to 2-3 positions after the computer discharges. This will clear all the BIOS data. This must fix the issue of the CPU not being detected in MSI MPG Z490.

Ernie Lo

Ernie Lo is a qualified web designer and web developer. He works as an IT support technician and website manager at Benleigh Vending, and he also fixes vending machines.

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