10 Reasons and Fixes to Loud PC Fans When Idle

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)!

Reasons for loud PC fans when they’re idle include dust accumulation, poor ventilation, malware attacks, corrupt processes, and incorrect placement. Sometimes, faulty or smaller fans tend to be noisy. Upgrade your PC’s software, move the computer, or change some hardware to fix these issues.

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.

Read on for more information on the types of fans on your PC, why they tend to get loud when idle (and not), and ways to fix them. 

fast spinning fans inside a computer

Loud PC fans when idle

Most PCs come with two types of fans: case (computer) fans and CPU fans. When you turn your computer on, it generates heat, which only increases with the number of applications running and the nearby environment’s temperature.

These fans play a critical role 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, either fan can cause noise while your PC is idle, as outlined below.

Computer case fans loud when idle

Case fans can sometimes generate a low hum. However, a loud fan can also symbolize a computer fan that’s 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

fast spinning cpu fan

The CPU fan helps in cooling 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 fans and CPU fans are designed to cool different PC components, they share quite a few 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

a cpu heatsink's find clogged with dust

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

Regardless of how much you keep your working surfaces clean and empty, dust will work its way into your PC. After all, when your skin cells die, they release 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

cleaning computer fan with a small paintbrush

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 amount of 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, not to mention it makes the whole job easier too.

2. Poor ventilation

fan intake filter blocked with dust

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 when it detects excessive heat as a self-protection mechanism.

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

humorous joke about a girl about to use leaf blower to clean out computer

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, make sure that you are grounded and the device you are using 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

symbolic representation of malware

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 continues to replicate, 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, it’s best to install a malware detection and removal tool.

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

In some cases, 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 is enough to make 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 comes in handy when you need to open the Activity Monitor on Mac. These two programs can help you determine which programs are using most of your CPU resources and storage at the moment. You can end all processes that 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

laptop placed on bed

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 your computer 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 amount of air is insufficient. Your PC may release less heat than it should, forcing its fans to work harder. Therefore, it’s 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 also comes in handy when you need to blow cool air towards 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 comes with rubber feet on the bottom. These extras allow some space between your PC’s casing and the surface, which helps when your computer 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

symbolic overclocking computer hardware

Simply put, 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 sure-fire way to overheat your computer’s components. As a result, your PC’s fans have to rotate faster to dissipate the heat to 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, when the two become outdated, your system may not perform optimally. 

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

pc case with fan on side panel

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 that ensure all critical components get 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 earlier, 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 so that it gently rests around the fan blades to avoid contact. 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

high end graphics card and ram inside pc

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 noise while idle due to the GPU or memory? If it does, a specialized fan can come in handy. 

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

10. Faulty fans

the inside of a computer fan

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 that you can’t ignore. A drop of sewing machine oil may help in such instances if applied immediately.

This seldom is an adequate fix. I recommend that you swap 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 the fans 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 only 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. The fans 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. If your PC is silent and produces no airflow, chances are the fan is broken. If you feel a gentle flow but hear the fan rotating quite fast, it may be obstructed.
  • 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.

For more information on how to check if a PC fan is working correctly, we recommend you watch the following video:

YouTube video

Summing up

If left uncontrolled, overheating can cause irreparable damage to your computer. Functional fans come in handy at the end of the day by ensuring your unit works efficiently within a safe temperature range.

To keep your fans noise-free and effective, ensure you do the following:

  • Regularly remove accumulated dust from your PC.
  • Keep the air vents unobstructed for proper ventilation.
  • Restore factory settings if you’ve overclocked your computer.
  • Regularly update software, including BIOS and device drivers.
  • Install antivirus software to remove programs taking up memory and space.
  • Close all unnecessary background programs using Task Manager.
  • Replace all faulty fans immediately.
  • Make sure fan profiles are configured correctly either in the BIOS, controller software, or hardware.

After going through everything here, I’m sure you will get your computer quieter at idle than ever before.