How to: Quieten a noisy PC

There are numerous ways to reduce the noise made by your PC, and for not much money. By reducing the speed of your case fans, using a larger, quieter cooler, or adding sound-absorbing foam, you can drastically cut noise without having a huge impact on cooling. To test the effectiveness of these methods, we’ve used a sound meter to measure the impact of our tweaking, which measures the noise level while resting on the top fan vent of the case. The ambient noise level was recorded at 30dBA – the minimum level we can test.

Configure EFI or software

The latest fan control options in EFIs and Windows software utilities are very useful for controlling fan speeds, both with 3-pin and 4-pin PWM fans. Some motherboards, especially boards with an Asus EFI, can actually stop a fan spinning all together, as long as the CPU temperature is below 75°C. 

You can tweak this setting in the EFI or Asus’ Fan Xpert utility. For 3-pin or 4-pin fans, you can run the fan tuning option, which gives the software the information it needs to control your fans accurately. 

You can then use it to stop the fan completely below certain temperatures – which is great for creating a silent PC under certain circumstances. 

Alternatively, you can just run the fan at very low speeds and tweak the fan curve to increase the speed as the temperature rises. We noticed the fan speed reading for 3-pin fans wasn’t particularly accurate, though, so check the fan is actually spinning when it’s set to spin at a very low speeds. You can control the speeds of chassis fans or a CPU cooler fan here, but the latter is limited to a minimum speed of 20 per cent in Asus EFI systems.

Noise levels

  • Max speed    40dBA
  • Minimum speed    30dBA 
  • Fan switched off    30dBA

At maximum speed, you can hear this fan spinning. At its lowest speed, though, the case fan was inaudible outside of the case, and while the airflow was significantly lower than at maximum speed, it adds a significant amount of cooling potential to the system.

Use a resistor cable

Noctua NA-SRC10
$12 (box of three cables)

There’s a much simpler way to reduce the noise your fans make than fiddling around with software. A resistor cable can be inserted between the fan cable and motherboard, reducing the supplied current to the fan. This method can work with fixed fan speeds and variable fan speeds, although you’ll get more flexibility using the EFI software.

Noise levels
Max speed    40dBA
Minimum speed    35dBA 
Fan switched off    30dBA

We used a Noctua NA-SRC10 resistor cable, which saw a decent drop in noise from maximum speed while still dishing out reasonable airflow. However, it isn’t as quiet as an EFI-tuned fan.

Don’t use a hard disk

If your PC is already very quiet, you may have noticed just how much noise comes out of your hard drive. You can consider using a hard disk enclosure to muffle the noise, but these enclosures can be large and expensive. Dropping from a 7,200rpm model to a 5,200rpm drive won’t help much either, as slower drives still make noise. The best way to kill the noise is to go solid state with an SSD. 

Noise levels
Hard disk        40dBA
SSD        30dBA 
Ambient        30dBA

Hard disks aren’t that noisy compared with high-speed fans, but the clicks they make while being accessed can be very annoying. The general whine from the disk equated to around 3dBA with the sound meter sitting next to our silent PC, peaking at 35dBA when the disk was being accessed – that’s less noise than most fans, but the hard drive is clearly still a source of noise.

Reduce graphics card fan speed

Not all graphics cards can switch off their fans completely, but if you head to the Fan tab in the MSI Afterburner settings, you may find you can lower the fan speed to zero, or at least run the fan at lower speeds than normal. 

We found an XFX Radeon R9 390X wasn’t able to completely switch off its fans, but we could prevent them from spinning up too fast too soon. For example, we set the fan speed to 20 per cent until the temperature reached 80°C, when the fan speed would increase to 40 per cent to stop the card from throttling. 

Noise levels
Auto fan profile        56dBA
Custom fan profile        48dBA 

Use sound-absorbing foam

Noise Dampening 
Kit $60

Sound-absorbing foam is used in a number of cases out of the box; it’s similar to packing material, and if you use enough of it, you can deaden the sound from your PC, reducing the noise that hits your ears. 

Overclockers UK offers built-to-order kits for a variety of cases, from the BitFenix Prodigy to the NZXT Phantom 820, as well as offering universal kits that you can cut-
to-size. Unfortunately we could not find any Australian shops selling such kits, but you can have this shipped to you.

Noise levels
No foam        38.5dBA
Full foam kit    36.5dBA 

We honestly didn’t expect the sound-absorbing foam to make much of a difference to the decibels, but there was a clear drop in the noise level once we’d added the sound-absorbing foam to our system. With all the fans set to standard levels, the sound meter registered 38.5dBA, but this result fell to 36dBA with the sound-absorbing foam. 

The effectiveness of this method will depend on the case you use, of course, as any mesh panels will mean more sound can escape the case.  

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