How To Fix CPU Fan Not Detected [CPU Fan Error]

The 511 CPU Fan not detected error is a common Windows problem faced by PC users.

I know how frustrating it can be to face this issue after setting up and installing brand new cooling fans. I’ve experienced this issue a couple of times myself. After digging into it and trying out different tricks, I was able to resolve this problem for good.

There’s nothing to worry about as the solution is extremely simple. I have compiled an entire guide that will walk you through all the fixes that are guaranteed to help you get rid of this issue completely.

The CPU fan not detected in BIOS error usually appears when your computer fails to detect your CPU fan, or maybe your CPU fan fails to function. Either way, you’ll be facing this error whenever you boot your computer.

The possible reasons for why this may be happening could be damaged CPU fans, dust-filled fans, damaged heatsink, and anything else that compromises your cooling fan’s function.

BIOS settings of your computer could also be the main culprit responsible for the problem.

Although the problem may seem complicated to you, I promise that by the end of this guide, you’ll know exactly what to do to get it resolved. So, stick with us till the end and get rid of the 511 CPU fan not detected error for good.


What Is The 511 CPU Fan Not detected error?

The 511 CPU fan not detected error means your system is unable to detect or connect with your CPU fan. This may be due to a failure of the CPU cooling fan, or maybe the fan is simply just disconnected.

Physical damage to the cooling fan could also prompt this error in the BIOS. In this case, you will have to get the cooling fan repaired or replaced for your cooling system to start functioning again.

The proper working of your CPU fan is essential for your computer. Without them, your computer would simply overheat, resulting in compromised performance. You’ve probably noticed that you received this error after the shutting down of your computer on its own.

This happens due to overheating when the fans fail to keep the PC components cool. The system usually shuts down on its own to protect the PC from damage.

In extreme cases, the high temperatures could cause permanent damage to your hardware, which could create major problems for your PC.

Why Is My CPU Fan Not Being Recognized In BIOS?

There could be plenty of reasons why your CPU fan is not being recognized in BIOS, leading to the 511 CPU fan not detected error. The following are the main reasons responsible for this error:

  • Your CPU fan may not be recognized in BIOS because the CPU is probably not plugged into the fan header. You may also have plugged in the incorrect fan, which could lead to this error. Anything other than a CPU fan plugged into this header will lead you to this error. Other than that, if you have plugged in some other fan, such as a PWM fan or a cooling fan, you’ll notice your PC reaches high temperatures very quickly.
  • Physical damage to the CPU fans, motherboard, or heatsink could also trigger the 511 CPU fan not detected error. In this case, you’ll have to check your CPU fan to confirm any damage. The only solution in such a case is to repair or replace the damaged fan.
  • Dusty and dirty CPU fans can also give rise to this error. If you find your CPU fans dirty, you’ll have to get them cleaned to function normally.
  • Weak and loose connections of your CPU fans may also prompt this sort of an error. A weak connection won’t allow your system to detect any fans connected. Therefore, it is important to ensure your CPU fans’ connections are well secured.
  • At times, BIOS settings may cause this error to appear. Customized BIOS settings can trigger the 511 CPU fan not detected error for some reason. Therefore, you’ll have to reset your BIOS settings to default in order to get rid of this problem.

It is important for your BIOS to detect your CPU fan. This way, you can have control over your fan to gain the best performance from it. You can adjust the speed of the fan from your BIOS settings.

This can be very important for performance gains. It is important to fix this issue as soon as possible, and we’ll show you exactly how you can do it.

Fix For CPU Fan Not Detected Error

There are multiple ways to fix the CPU fan not being detected problem. It all depends on the root cause of the problem. So, if you are able to identify the cause of the problem, the solution for it will be a piece of cake.

This guide will simplify everything for you so you can eliminate the error in the easiest way possible.

Before proceeding to the fixes, it is very important to ensure your fan is intact and running well. This is necessary because if your fan is damaged or dysfunctional, none of these fixes will work for you. Instead, you’ll have to get the fan repaired or replaced.

Nevertheless, let’s move on and dive right into the fixes for the 511 CPU fan not detected error:

Ensure There’s No Physical Damage to The Fans

As already mentioned above, the CPU fan not detected error may arise due to any sort of physical damage to the CPU fans, motherboard, or heatsink. In such a case, you’ll have to examine your CPU for any sort of damage.

To do this, you must unplug your PC and open up the case to search for any physical damage. You can check out the fans, its rotors, the motherboard, and the heatsink for any sort of damage.

If you do not know how to check your PC from the inside, it is best you take the PC to a technician and have him take a look at it. If your CPU fan is diagnosed with any sort of physical damage, you will need to get it repaired to get rid of the problem.

Once the damaged part has been repaired, the error should go away on its own. In case the damage is irreparable, you will have to get the damaged part replaced.

If there are no signs of physical damage and you’re still facing errors, there could be multiple other reasons for these problems. Move on to the next fixes to see which one works for you.

Update BIOS To the Latest Version

The BIOS settings may rarely be responsible for the malfunctioning of your CPU fans, but they can be held responsible in some cases. An outdated BIOS version can also cause such errors.

You’ll be very lucky if only the BIOS settings are the reason holding your fan from being detected and functioning normally. You can easily fix it by updating your BIOS settings by following the steps below.

The following are the simple steps to update your BIOS:

  1. Launch your preferred web browser.
  2. Click on the search bar and type in System Information.
  3. Next, you’ll have to open it and find the field that goes by the name System Manufacturer. You’ll be able to see the name of your manufacturer right next to it.
  4. Once you’ve found your manufacturer’s name, go ahead and type it in your browser and also type BIOS with it. Then click Enter.
  5. Go ahead and click on the first result that pops up. You’ll be directed to a page where you’ll have a download option available. Go ahead and click on it to initiate the downloading process.
  6. Once the download is complete, extract the files in the folder. You can use applications like WinRar to complete this task.
  7. Next, you must copy those files to a USB drive for safekeeping. After that, reboot your computer to apply the updated BIOS.
  8. You can use the menu to update the BIOS on your computer. Your computer should automatically detect the file for an update as long as you’ve kept your USB plugged in.

And there you go, that’s how simple it is to update your BIOS. Hopefully, this will have resolved your issue. If not, proceed to the next solution.

Reset BIOS Settings

If you have customized the BIOS settings on your computer, this may be the main reason why your CPU fans keep failing. This may lead to the 511 CPU fan not detected error in some instances.

If you suspect this reason to be the main culprit, you can try resetting your BIOS settings back to default. This can help resolve your issue.

Follow the steps below to reset your BIOS settings:

  1. Launch your BIOS settings on the startup of your computer by clicking the dedicated key.
  2. Navigate to the Reset to default option and click on it.
  3. Once the settings have been reset back to default, reboot your computer.

Hopefully, after resetting your BIOS settings, your issue will be resolved. If not, move on to the next fix.

Use An Appropriate Fan

At times, users knowingly or unknowingly use a fan that is not a dedicated CPU fan. A CPU fan functions differently from other cooling fans as it spins much faster to cool down the components while the computer runs.

When people use other fans such as case fans or PWM fans in place of CPU fans, your PC may start to heat up more than usual, and your BIOS will fail to detect it. This is because the fan’s speed is much less than the speed normally produced by a CPU fan.

You will have to switch your fan with a proper CPU fan to fix this problem. Once you install a CPU fan, this should resolve your issue for good.

Clean the CPU Fans and Heatsink

There is a high chance you’re facing this error due to the buildup of dirt and dust inside your CPU fan. Dust can compromise the performance of your fan and can prevent the normal functioning of components, leading to the 511 CPU fan not detected error.

So, if you think this scenario applies to your current problem, you can try cleaning the internals of your CPU fans along with the heatsink to see if this fixes the problem.

For cleaning, you can utilize a blower or a can of compressed air to blow away the dust off your CPU fans and heatsink. First, shut down your computer and have it unplugged.

Once done, proceed to clean the dust from your components. Make sure to clean the fans while rotating to prevent any sort of damage to the components.

Once the cleaning work has been completed, you can plug in your PC and see whether the issue has been resolved.

If the issue still persists, try the next fix, which could prove very crucial.

Check CPU Fan Connections

Loosely connected cables or cables inserted in the wrong socket may also produce the 511 CPU fan not detected error. This is because your PC cannot detect an improperly connected component, resulting in such an error.

Thus, making sure your cables are perfectly secured and connected can help you resolve this problem. Follow the steps below to learn how you can perform this procedure:

  1. First of all, shut down your PC and unplug it from the electricity source.
  2. Next, open up the case and check the cable connections. Disconnect and reconnect each cable to secure it perfectly in its place. Also, check for any faulty cables which may trigger this error.
  3. Once everything has been checked, reboot your PC to check if the issue is resolved.

Hopefully, with all these fixes available, at least one will have worked for you. If none of them have worked, try consulting a certified technician to have them get the job done professionally.


How do I fix my fan not being detected?

You can try out the following fixes:

  1. Ensure There’s No Physical Damage to The Fans
  2. Update BIOS To the Latest Version
  3. Reset BIOS Settings
  4. Clean the CPU Fans and Heatsink
  5. Check CPU Fan Connections

All of these fixes have been explained in detail in this article.

What does it mean when the computer says CPU fan not detected?

The 511 CPU fan not detected error means your system is unable to detect or connect with your CPU fan. This may be due to a failure of the CPU cooling fan, or maybe the fan is simply just disconnected.

Physical damage to the cooling fan could also prompt this error in the BIOS. At times, BIOS settings or an outdated BIOS may also be held responsible for it. Moreover, dust or dirt can also be held responsible.

How do I force my CPU fan to start?

If you want to force start your CPU fan, first, you’ll have to access the BIOS as mentioned in the article above. After that, navigate to the fan settings section. Inside the settings, all you have to do is toggle the Smart Fan option, and you’ll be set to go.

Can the CPU run without a fan?

Yes, your CPU can technically run without having a fan installed. However, I recommend you avoid any act of such type as it can permanently damage your CPU and other components.

 How do you clean a CPU fan without removing it?

First of all, switch off your computer and unplug it as well to cut off electricity. After that, you can use a blower or a compressed air can to blow away the dust from the fans.

You may clean the blades with a cloth or a cotton swab. Try to be as careful as you can because these components are quite delicate and can be damaged easily.


It is normal for your computer to heat up while operating. However, things get critical when your computer heats up beyond a certain limit. To keep the internals of a computer from overheating, it is important to have the appropriate CPU cooling fan installed.

The 511 CPU fan not detected error could be a frustrating issue that can compromise the performance of your PC. Therefore, it is important to resolve it as soon as possible.

This article outlined all the reasons for why you might be facing the CPU fans not detected issue in your BIOS.

Make sure you follow each step carefully and correctly. If you do not know how to perform certain steps, you can have a professional technician take a look at it.

Hopefully, you will have found this article helpful, and your CPU fans not detecting issue will have been resolved. We wish you all the best.

Normal CPU Temperature While Gaming
Do New CPUs Come with Thermal Paste?
How To Increase Fan Speed On Laptop And PC
Best LGA 1151 CPU [Socket H4 / Socket LGA1151 / Socket 1151]

Nick Miller

It's Nick Miller a 25 year old tech enthusiast and senior editor at Flexgate, i try to make tech simple for the everyday person. You will find review about tech, tools and Computer hardware here.

Leave a Comment