ASUS CPU Fan Error!” is flashing on your screen, and your computer won’t start?

Nothing is more aggravating than turning on your computer only to be greeted by a confusing error message that prevents you from doing your job (or having fun).

Sometimes the problem is simple to read and rectify, but more often than not, you’ll have to manually copy-paste it into Google to figure out what’s going on.

The Asus CPU Fan Error seen on Motherboards from ASUS and other brands fits into both of these categories — the cause is evident, but the repair isn’t always as simple.

In fact, you may get this warning even if your CPU cooler is plugged in and working correctly.

Be Easy!

We’ll go over the most prevalent circumstances that might be creating the problem in this post, as well as suggestions and strategies for fixing each one.

We’ll also go through the sorts of situations in which a straightforward remedy isn’t achievable, and what that means for you in the future.

Why do I get the “CPU FAN Error” message in POST?

The error message “CPU FAN Error” in POST indicates that the system has failed to identify the FAN.

To fix the problem, follow the procedures listed below.

What does the “Asus CPU Fan Error” Mean?

The Asus CPU Fan Error Message is the motherboard’s way of informing you that it hasn’t detected a cooling device for your processor.

Because operating a CPU without a cooler is a surefire way to ruin your processor’s integrity, the motherboard prohibits the PC from booting.

It’s a crucial motherboard safety feature that prevents your CPU from overheating.

It protects naive PC builders from causing irreversible harm to their hardware.


“Asus CPU Fan Error”: What Causes It and How to Fix It

Let’s look at some of the most prevalent reasons for the CPU Fan Error now that we have a better understanding of what it entails.

Spoiler alert: Despite a CPU fan being hooked into the right fan header, a handful of them causes the error to display, thus the obvious option may not always be the correct one.

CPU Fan Isn’t Connected Properly

The most typical cause of this problem is that a fan is not connected to the CPU FAN header on the motherboard (or is not connected correctly).

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This implies that even if your CPU cooler’s fan is hooked into another Fan Header, such as SYS FAN (System Fan) or CHA FAN (Chassis Fan), you’ll still see the error notice if no fan is plugged into the CPU FAN header.


Check that the CPU cooler is correctly mounted in the motherboard (backplate, screws, Thermal Paste, Heat-Spreader Cover removed, etc., depending on the CPU Cooler) and that the CPU cooler’s fan is precisely hooked into the CPU FAN header.

It’s worth noting that you could not get the error even if the fan isn’t plugged into the correct socket.

Still, the issue might emerge at any time, resulting in your PC’s failure to launch and a lot of uncertainty.

To discover the CPU FAN Header, consult your Motherboard Manual or study the fine print on your Motherboard.

It’s commonly found near the CPU’s Socket in the upper right corner.

The CPU FAN (left) and CPU OPT (right) headers on an MSI Unify Motherboard are circled in red in the image below. Because they’re frequently close together, double-check that you’re using the right one.


The CPU Fan Header has an AIO Pump Installed.

If you wish to use an AIO liquid cooler instead of an air cooler to cool your CPU, you’ll need to attach a radiator fan – or even a case fan – to the CPU FAN header.

This allows the motherboard to detect the presence of a fan, protecting the CPU from overheating.

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When installing an AIO liquid CPU cooler, a typical error is not connecting the fan to the CPU FAN header or not wiring the pump into the correct AIO PUMP header.

Thankfully, properly connecting the AIO pump to the motherboard, is a fairly quick and straightforward remedy.

Connect the AIO Radiator Fans to  CPU  FAN  and the Pump to AIO PUMP.

BIOS isn’t up to date.

Strangely enough, not having the correct BIOS version loaded is another issue that ASUS claims might cause the error to appear.

Of course, this isn’t the first time a missing BIOS update has caused a component to vanish, but it’s still weird.

Still, it’s a good idea to keep your BIOS up to current, and ASUS and other Motherboard Manufacturers offer a variety of EZ Update options to assist you.


If your motherboard supports it, you may update the BIOS using an EZ Flash Update or an internet connection.

This link will take you to ASUS’s instructions, however, this Byte Speed article will also lead you through the procedure with the help of some additional visual features.


CPU Overheating

The motherboard may trigger the CPU Fan Error if your CPU is not getting the appropriate cooling it needs, either because the CPU cooler is inadequate or because the CPU is overclocked.

This is done solely as a preventive measure, and the system should be interpreted as a warning.


There are a few things you may do to remedy this problem, but first, make sure you don’t have any overclock settings left, or erase them if you do.

Next, make sure your CPU cooler’s fan is working and that it isn’t clogged with dust or other obstructions.

If you’re utilizing an AIO cooler, check for any tiny coolant leaks that might be the source of your overheating problems.

You should also consider replacing the thermal paste between your CPU and the cooler, particularly if it has been in use for more than two to three years.

Our information on how long thermal compounds last and how to replace them can be found at the following link.

Also, check sure you’ve removed any plastic covers that the manufacturer may have stuck to the underside of your new CPU Cooler.



If none of the aforementioned methods worked, the problem might be due to a manufacturing flaw in one of the components.

As much as we hate to be the bearer of bad news, the reality is that such flaws do arise, although they are quite uncommon.

Any mechanical or electrical component is prone to inheriting faults from the production process or degrading over time.

To narrow down the options of what could be the source of the problem, consider inserting a Case Fan into the CPU FAN Header as a temporary measure.

However, you should not boot into your system in this scenario.


The CPU cooler’s fan may be dead on Arrival for a select few (DOA).

To seek an RMA, you must first contact the seller (Return Merchandise Authorization).

Of course, this is one of the most frustrating aspects of assembling a new PC, but the chances of it happening again are quite remote, so there is some comfort in that.

Try inserting an alternative fan into the CPU FAN header and seeing if it boots properly to verify sure the CPU cooling fan is indeed dead.

However, do not use the PC in this setup since the CPU will not be properly cooled.


Aside from the rare incidents of a cooling component failing or arriving dead on delivery, a CPU fan problem on a Motherboard shouldn’t be too difficult to diagnose.

This issue merely indicates that your Motherboard has failed to identify a CPU Fan.

If your BIOS is current and your air or AIO cooler is correctly installed, the problem should be resolved quickly.