Red CPU Light on Motherboard Fixes & Diagnosis – Detailed Guide

What does it mean when you turn on your computer and the red CPU light on your motherboard comes on? You might be thinking that this is a sign of doom. In reality, though, it just means that something needs to be checked on the inside of your computer. This can happen for a variety of reasons such as overheating, RAM not being in the right slots, faulty RAM, CPU Cooler not properly placed or an with the boot devices not being detected. Thankfully, there are many ways to troubleshoot this problem and get back up and running again quickly!

A lot of people get confused when they see the red light on their motherboard and most think it’s related to their CPU, that they didn’t properly place their CPU or something similar, but from our experience that’s not always the case, more often than not it’s an issue with other components being faulty or not properly placed/connected.

If your motherboard actually has a label saying “CPU” and the red light shows there, in that case it really is related to the processor. But there can also be a few different reasons for that, don’t always assume a faulty CPU.

Why is there a solid red light on my motherboard?

If you are seeing a solid red light on your motherboard, it is most often an indication that the board has failed to boot properly and needs to be replaced or one of the components may be faulty or not properly plugged in. The system may not boot or have other issues as well. As such, continue reading this article and try the fixes that we recommend as they will often fix any issue. If the fixes we recommend don’t work or if you don’t feel confident trying them yourself, please contact technical support for assistance with determining if there is a hardware problem and resolving any potential warranty conflicts.

What Does The Red CPU Light on Motherboard Mean?

If your motherboard actually has a label saying ‘CPU’ with a red light above/underneath it then it really might be related to the CPU, if that’s not the case, then it’s likely an issue with some other component in that case, please try the other fixes after trying the ones we will mention below related exclusively to the CPU.

If your motherboard has a label that really does say CPU then there are a couple things you can do to try and fix it:

1- The cooler may not be properly plugged in. If this is the case, grab your cooler and try to move it, if it’s properly plugged in it wont move at all because it’s properly attached to the motherboard. This is one of the most common issues.

2- Try removing 1 RAM Stick and try to boot with only 1 connected, if that doesn’t work, unplug the remaining Stick & Plug the one you removed previously, this way you’ll test if one of the RAM Sticks are faulty. Although they aren’t entirely related to the CPU, RAM often shows up as a CPU problem. If you manage to boot with 1 RAM Stick then it means that either:

  • The other stick is faulty.
  • You didn’t plug the RAM in the appropriate spots
  • Incompatible RAM?(If they’re different)

3- CPU Power cable not properly connected to the motherboard. Make sure that it’s properly connected otherwise the CPU won’t be able to get any power to run hence the error.

4- PSU can’t provide enough power for the CPU to run properly. This is rare and if everything else is powered then it most likely isn’t the reason but it’s still a possibility. The PSU can be faulty and only be able to provide a tiny bit of power, just enough to power up some components from the motherboard and not enough for the processor, if that’s the case, try with a different PSU if possible.

If none of the above then it really might be a bent pin on your processor or simply faulty and you may need to return it for a new one or check an article on the scope of fixing bent pins if that’s the problem.

Diagnosing the Red Light On The Motherboard

If your motherboard simply shows a red light and has on labels to identify exactly what component its having issues with, then there are a few things you can do to diagnose & fix the possible issue.

The first step in finding help for your computer problem begins with determining what type of fault was detected by our computers when they were turned on ̶ whether that be power supply failure, memory errors, fan issues etc…

Start with the basics, Plugging in all cables correctly and making sure everything is plugged into its proper connection as that’s often overlooked as possible sources for problems but can contribute significantly to fixing any issues.

If everything is properly plugged then you can:

  • Do a RAM Faulty check as that’s most commonly the issue.

Try to boot with only 1 RAM Stick, if it doesn’t work, unplug it and plug the other one and try again. If neither the RAM sticks work then make sure they’re properly plugged & in the correct slots.

  • Make sure the GPU is properly plugged into the motherboard.

Some people don’t plug in the GPU well enough and it triggers the red light error, you may need to apply a good bit of force on the GPU until you are sure that it’s properly plugged.

  • Make sure it’s not a problem with the PSU being faulty or not powerful enough.

If the motherboard gets powered, try removing either the CPU or the GPU and see if the red light goes away (if the other one gets powered). The PSU might now be powerful enough to sustain the power consumed by both the CPU and GPU.

  • Unplug GPU completely and try to run.

You should be able to run with only the CPU and its integrated graphics, if that works it may be an issue with the GPU not being plugged in correctly(motherboard detects GPU being plugged but it’s not fully plugged in properly) or faulty GPU.

  • Check the CPU Cooler.

Check if it’s properly plugged to the motherboard, grab it and try to yank it, if it doesn’t move at all then it’s properly plugged, if it moves even a little bit it’s most likely not plugged in properly.

  • Reset the BIOS / Clear the CMOS

Your manual probably has instructions on this or you can check the manufacturer website. It’s essentially a silver’ish battery that you will need to remove for about 5 minutes and then plug it in again.

  • Unplug everything and try again

Just unplug everything and try to plug everything back in.

If none of the above works then it’s likely a problem with the processor (assuming you tried booting without GPU).

It’s extremely RARE for none of the fixes above to work, if that does happen though, you should contact some local ITs to give it a try and see if they can find the problem.


Thank you for reading. We hope this post has helped to fix your red CPU light problem! If not, we recommend consulting with a local IT specialist before giving up on the machine entirely. They may be able to diagnose and repair the issue without sending it away for repairs.

We invite readers who have had success or other advice about resolving this error code to leave comments below sharing their experience so that others can benefit from what they’ve learned too! Thank you again for reading our blog today!

1 Comment
  1. I recently had a booting problem, unplugged everything I read it might be online. Had a friend who is an IT tech and found that the video card was at fault. Not a hard fault but intermittent.
    He changed it out and I’m back in business. Darn computers… 😂

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