PC Fans Loud When Idle (Causes & Fixes)

Without a doubt, the fan is the loudest component of a PC. This is because it’s designed to spin faster when your computer’s activity level increases, cooling all interior components. However, if you notice your fans getting loud when the PC is idle, there are a few common reasons (and fixes).

Note: This article assumes that your fans have been correctly configured (fan speed vs temperature curve), by means of the BIOS, or by any other fan controller hardware or software.

Causes Of Idle PC Fans That Are Loud

There are fans in a computer for these areas:

Turning your computer on generates heat, which only increases with the number of applications running and the temperature of the nearby environment.

These fans are critical in cooling your computer down, ensuring its processes run smoothly.

One common thing to look out for is a stray cable touching against fan blades as they rotate. This can cause a bad noise and is so easily fixed.

Therefore, as outlined below, either fan can cause noise while your PC is idle.

Computer case fans are loud when idle

Case fans can sometimes generate a low hum. However, a loud fan can indicate a computer fan is about to fail.

The stereotypical sign is when any of the fans attached to the front or back of your computer produce a clicking or high-pitched noise.

CPU Fan loud when idle

The CPU fan helps cool the processor by pulling or blowing air through the CPU heatsink fins. It’s common for these fans to go from silent to loud when you’re working on your computer or playing a game.

Generally, they should only produce a slight hum. Any additional noise could indicate a loose fan, the fan hitting an object, or a faulty fan.

Although case and CPU fans are designed to cool different PC components, they share several similarities regarding why they get loud.

Here are ten reasons your desktop or laptop computer’s fans make noise and how you can fix them at home:

1. Dust

Dust is one of your computers’ greatest enemies. You’ve probably heard this countless times, but the reality is that it’s inevitable.

Dust will work into your PC regardless of how much you keep your working surfaces clean and empty. After all, when your skin cells die, they are released into the environment in dust form.

Excess dust on your computer makes it hotter. As a result, your PC’s fans must spin faster to keep it cool, causing the noise. The situation could be even worse if you own a pet or smoke in the house!

How to remove dust from a computer

Important: Before cleaning out your computer, please wear safety glasses and a mask.

The trick is to grab your screwdriver, open the PC, and clean the dust with an electric or air duster, depending on the accumulated dust.

However, you should clean the filters frequently and replace them if they fall apart. Also, consider ear protection since this duster is quite loud. Alternatively, you can install filters on your intake fans to prevent dust buildup in your PC in the future.

I also recommend using a small paintbrush to get the last bit of dust stuck on the fan blades and all the nooks where dust is trapped.

This will make a big difference in the final result of your cleaning and make the whole job easier, too.

2. Poor ventilation

Your PC needs proper ventilation to work efficiently. On the contrary, restricted airflow can cause severe performance issues, such as the processor and hardware overheating, which may cause a system failure.

Most notably, the processor tends to slow down as a self-protection mechanism when it detects excessive heat.

Inadequate ventilation can arise from dust accumulation, poor PC storage, and insufficient clearance around the air vents. As a result, it forces your computer’s fans to work harder, resulting in a clicking noise.

How to clean your PC’s air vents

To clean your PC’s air vents, follow these steps:

  1. Shut your computer down and disconnect it from the sockets.
  2. Inspect the vents, checking for dust and debris.
  3. Using a can of compressed air (or compressor), clean all dust and debris from the air vents, cooling fan fins, and dust filters.

When doing that, ensure you follow these guidelines:

  • Don’t use a vacuum cleaner or blower to protect your PC from damage by static charges. However, if you must, ensure that you are grounded and that your device is well-earthed. Avoid direct contact with any components while you are using such devices.
  • Don’t blow the dust by mouth to avoid depositing moisture on your computer’s components.
  • Follow all instructions on the compressed air can to avoid damaging your PC.

3. Malware infections

Computer viruses and worms can make your life a living hell. These malware infections don’t just slow down your computer; they can also overwork your hardware, causing irreparable damage.

When malware infects your PC, it may take up a significant portion of the storage and other resources. Then, as it replicates or continues its task, it eats up even more space and resources.

For instance, some adware may hold the CPU hostage as they stream in pop-up ads. Or, some programs may force your PC to mine cryptocurrency for a hacker, triggering overheating.

As a result, your fans’ blades may rotate faster to keep the unit’s temperature at the required levels, leading to that unusual noise.

How to prevent malware infections

To prevent malware from holding your computer hostage, installing a malware detection and removal tool is best.

Downloading, installing, and running the free version of Malwarebytes goes a long way to remove unwanted malware that a lot of antivirus software doesn’t detect.

4. Corrupt processes

Sometimes, your CPU fans may make a loud noise when corrupt processes overburden the processor. According to HP, one of the leading PC manufacturers, an unnecessary process consumes 1% to 100% of the CPU.

The company states that a constant 3% load makes your PC’s fans spin faster.

How to exit excess processes


Are you a Windows user? If so, simultaneously pressing Ctrl + Shift + Esc can open the Task Manager, which shows all the software currently running.

Alternatively, Ctrl + Space is handy when opening the Activity Monitor on Mac. These two programs can help you determine which programs currently use most of your CPU resources and storage. You can end all processes you’re not using to reduce the strain.

Pro Tip: It also helps to download temperature monitoring programs — such as Core Temp for Windows or Temp Monitor for Mac — to see whether your CPU is overheating.

5. Improper placement

Where and how you place your computer can either help it cool down or cause it to overheat. For example, in some cases, you may be tempted to place it in an enclosed space — such as your cabinet or drawer — as you take a breather.

However, by doing that, you confine it to a smaller place with less air circulation. Because of that, it may not cool to an optimal level.

As long as your computer is on, it requires enough cool air to circulate it to absorb the heat it produces. Then, as the fan spins, it distributes the heat to the air, cooling your PC.

However, that can be a challenge if the air is insufficient. Your PC may release less heat than it should, forcing its fans to work harder. Therefore, it is critical to ensure your computer is in a location that helps it cool down.

This principle also applies to your laptop. It’s better to place it on your desk or table when using it, and if you have to put it on your lap, ensure it spends as little time there as possible.

A laptop cooling platform is also handy when blowing cool air toward your computer. Or, you could use cooling pads to prevent your laptop from overheating as you use it on your lap.

Also, ensure your laptop or computer’s casing has rubber feet on the bottom. These extras allow space between your PC’s casing and the surface, which helps when it releases heat.

Always check if the rubber has worn out or fallen off, and replace it immediately to keep your machine in the best shape.

How to prevent overheating

Always place your computer where its vents aren’t obstructed by items that can cause overheating, like fabrics. As a rule of thumb, place your PC on flat, stable surfaces to ensure airflow remains uninterrupted.  

Tip: If you use your laptop outdoors, minimize exposing it to the sun. Too much exposure to solar heat causes excess temperatures and even louder fan sounds.

6. Overclocking

Overclocking refers to taking your PC’s component, like the processor, and running it at a higher specification than the manufacturer’s rating. In other words, you run your computer faster than it’s designed to handle.

Overclocking is a surefire way to overheat your computer’s components. As a result, your PC’s fans have to rotate faster to dissipate the heat into the environment.

As a result, you overstretch your computer’s capabilities beyond its limits. If you do that without a high-performance cooling solution, your fans are certain to rotate faster and make more noise.

To fix this problem, it’s best to reconfigure your hardware to factory settings. Or, you can use larger, higher-performing coolers and extra case fans to improve cooling.

7. Outdated BIOS and device drivers

device manager listing devices

Your PC’s BIOS and drivers come with feature enhancements that keep its software updated and compatible with installed hardware. Unfortunately, your system may not perform optimally when the two become outdated. 

For instance, the CPU may strain, causing heating problems. This could create instability in your computer’s system and hardware, eventually causing fans to rotate faster. During that process, you may notice your CPU and case fans making a lot of noise.

To solve this problem, you should install the following:

  • A video card driver.
  • A thermal chipset driver.
  • A chipset driver.
  • BIOS.

8. Fans hitting the side panel of the case

Consider this scenario: Your PC has been idle for some minutes. Suddenly, its fans start rotating faster, making a rattling noise.

If you’ve had such an encounter, chances are there’s a fan hitting the side panel. This can occur when you install a bigger graphics card next to the panel. Ultimately, that can cause two problems: the fan hitting the side panel and the card heating up quickly. 

In such a case, you may attempt to keep the side panel off as a temporary solution. However, that’s more counterproductive and damage-inducing than anything.

Computers are usually designed to operate more efficiently with their casings intact. For instance, they come with air circulation systems ensuring all critical components are cooled effectively. Unfortunately, when you remove the side panel, you disrupt their built-in systems.

Also, leaving the case open exposes the fans and other hardware to dirt and debris. As mentioned, dust accumulation causes PCs to overheat, so you’d only make the situation worse by leaving the case open. Also, debris can clog the fans, causing more damage.

You can place some cushioning material, like foam or rubber, between the graphics card and the side panel to fix this problem.

But it’s best to stick it on the side panel to rest around the fan blades to avoid contact gently. However, ensure the rubber or foam isn’t so thick that it pushes the GPU too far, making the video card sit on its slot loosely.

9. Super-fast memory and high-end graphics cards

Although the CPU produces most of the heat from a computer, other components may produce intense heat, too, depending on their conditions and how well you maintain your PC.

For example, installing a high-end GPU or super-fast memory increases the amount of heat the unit produces.

Does your PC fan make a noise when idle due to the GPU or memory? If it does, a specialized fan can come in handy. 

You can install a memory fan if your computer is overheating due to memory issues. If the noise is because the graphics card is overheating, a graphics card fan may solve the problem.

10. Faulty fans

If none of the fixes we’ve mentioned help the noise issue, and you’ve exhausted all the options, you may need to replace the fans.

Sometimes, the fans may produce a clicking or grinding noise you can’t ignore. A drop of sewing machine oil may help if applied immediately.

This seldom is an adequate fix. I recommend swapping your PC’s fans with new ones because they don’t cost the earth.

Caveat: It’s critical to note that smaller fans are usually noisier, so don’t rush to prejudge the situation. Also, replacing them may void your warranty. Instead, do some research to determine if the fans need replacing and aren’t just noisy by design. Also, ensure you check the airflow and the noise levels of the replacements to determine if they’d fix the noise problem.

Ways to check if your PC fan works

Here are some effective methods of checking if your computer’s fans work correctly:

  • Listen for noise. If your PC’s fans function correctly, they should sound like soft propeller fans. Ideally, they should be incredibly silent if you have an efficient cooling system. They’ll rotate faster and louder when you’ve been running tasks for at least five minutes. Pulsating or screeching noises indicate a fan is broken or obstructed.
  • Feel for air. Feeling the air coming out of your PC’s vents indicates the fans are working. They should expel the air from the vents once the system picks up after booting. To check for airflow, put your hand one inch away from the vent, with your palm facing the PC. The fan is probably broken if your PC is silent and produces no airflow. It may be obstructed if you feel a gentle flow but hear the fan rotating quickly.
  • Watch for errors. Does your PC regularly restart unexpectedly, freeze up, slow down, Black Screen, or offer the dreaded Blue Screen of Death? If so, you may need to check the fan or any unit attached to the fan, like the heatsink.