Push/Pull produces loud whine but with one fan stopped it is quiet?

[starlight6]

I recently had a pair of NF-F12 PWM fans delivered for use in push/pull on my Corsair H80 radiator. I was previously using a pair of Akasa Apache's.

I was initially disappointed as when running at full speed they were much noisier than the Apaches and produced an annoying whining sound, whereas with the Apache's I'd just hear the heavy airflow.

However, I've since found that the annoying whining sound only happens when both fans are on. If I stop either one of the fans, the noise is drastically reduced. I then can only hear the airflow like with the Apaches, which I am happy with.

I know obviously two fans are louder than one but this is a huge difference with the entire whining sound disappearing when only one fan is running. It seems like maybe there is some interference between the two that is producing the whine.

Has anyone encountered this before? Since both fans seem to operate correctly on their own, it doesn't seem to be an issue of one being faulty. I'm not really sure what to do.

 

[airdeano]

on the corsair forum, there was a couple of instances using the factory H80 fans
creating a nausious noise. some had changed fans and the issue was repaired,
some it did not. because the H80 fan is high static, some believed the mesh in
between the fan and radiator was the culprit. but the thread died from lack of
answers. does the noise stop if the opposite fan is stopped?

airdeano

 

[CPMFW]

are the fans connected to a molex adapter?

 

[starlight6]

Airdeano, the noise stops if either the push or pull fan are stopped. It is only present when both the Noctua's are going at the same time.

CPMFW, they are connected via a PWM splitter cable to the 4-pin CPU fan header and then PWM was disabled to test them running at full speed. I've tested running them off different connectors too in case that was the issue though and it made no difference. Either fan alone is fine, but both on together make the noise.

Hopefully tonight I'll have more time to do some further experimentation. I'm thinking to check:

1) if the still make the noise without the rad in the middle
2) If replacing one of them with one of the Akasa Apaches I have gets rid of the noise
3) If swapping which one is doing push and which doing pull makes a difference

 

[CPMFW]

Hopefully tonight I'll have more time to do some further experimentation. I'm thinking to check:

1) if the still make the noise without the rad in the middle
2) If replacing one of them with one of the Akasa Apaches I have gets rid of the noise
3) If swapping which one is doing push and which doing pull makes a difference

sounds like a good plan mate... hope it works out right

 

[jibatron]

Hi i realize this thread is way old but i have the same issue! so im wondering if u found a fix? I have 2 nf-f12's on a H80. the whine pretty freakin loud when both are at full speed but if i turn of either one, witch ever fan f=remains running is very quite.

 

[MacLeod]

May be a dumb suggestion but have you tried swapping the fans? Maybe one is moving air just a tad different than the other and thats causing the whine. Maybe moving them to where the one that was pushing is not pulling will change it up enough that the noise will stop. Just a wild guess but worth a shot.

 

[Xploited Titan]

Have you guys tried to shroud one of the fans?

I somehow think it's the "sucking" fan that whines when both are on. The static pressure seems pretty high, so wondering if the first fan ain't blowing too hard on the second, compressing the motor hub and pressing the blades too close to the Focused Flow system, creating turbulence with a whining sound.