Noctua NF-A14 fans making undulating humming (not vibration)

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thraddy
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Joined: Sun Apr 22, 2018 12:31 am

Noctua NF-A14 fans making undulating humming (not vibration)

Post by thraddy » Sun Apr 22, 2018 12:36 am

I have 2 Noctua NF-A14 PWM fans on the front of my Fractal Design Define S. I chose them specifically as I hoped they were the quietest. But they make this undulating humming noise (sounds like vibration, but I don't think it is as I use the rubber mounts) which is very noticeable at around 700RPM (not really noticeable at higher RPMs as it's drowned out by the fan noise, and slightly less noticeable at lower RPMs, but I'm sure it contributes to the overall noise at any RPM).

It's annoying as shit! Especially considering I also have a 140mm Noctua fan on the CPU heatsink which is dead quiet, and a 120mm Noctua fan on the exhaust of the case which is very quiet and doesn't make the undulating humming noise.

I thought the fans were faulty, but now I realize that may not be the case - I've read similar threads that it's likely caused by the airflow being restricted or something, as well as others saying the problem is worsened due to the hexagonal holes on the Fractal Design cases (usually from people using them at the top of the case, but I use them at the front and there are no holes at all, it's empty space apart from the dust cover and then the case cover).

I've read that removing anything obstructing the airflow can help as it could be due to the turbulence, but I don't want to remove the dust filter for obvious reasons.

Will changing fans fix it? Unlikely I suppose? Is there anyone who had this problem and can help me resolve it somehow?

Abula
Posts: 3662
Joined: Tue Nov 02, 2004 12:22 pm
Location: Guatemala

Re: Noctua NF-A14 fans making undulating humming (not vibrat

Post by Abula » Tue Apr 24, 2018 12:35 pm

I also didn't like the nf-a14 pwm on a fractal dealing r4, but I don't have any fix for you aside from changing them.

Antec true quiet 140 for a budget oriented fan, maxes at 800rpms ornif you want pwm, be quiet silentwing3 bl067, maxes out at 1krpms.

thraddy
Posts: 2
Joined: Sun Apr 22, 2018 12:31 am

Re: Noctua NF-A14 fans making undulating humming (not vibrat

Post by thraddy » Mon Apr 30, 2018 1:02 pm

To be clear, it's only at around 500-800rpm that they make the weird turbulence/undulating noise.

Would adding spacers/grommets so they are deeper in the case, thus hopefully reducing turbulence through the front cover, help?? As this is apparently the cause of the noise.

Perhaps a different fan would help? I see in this thread viewtopic.php?f=9&t=70049 people are discussing the merits of the other models of Noctua fans for front of cases.

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