Throbbing noise when both fans run

[DanAri]

I have a Lian Li full size case, and I replaced the two intake fans on the lower part of the front with Gentle Typhoon fans. When both are running, I get a throbbing hum (whoom whoom whoom whoom), reminiscent of the USS Enterprise. If I stop either one of the fans but leave the other running, the throbbing stops. It's only when both fans are running. Pressing hard on the case of one fan or both fans does not modify the sound, so I don't think they're loose (they're both attached with metal screws to the metal frame of the case).

I'm guessing that there is some sort of constructive interference between the vibrations of the fans. Other than permanently turning one off, are there any solutions I should explore? I've already added accoustic padding inside the side panels, and that didn't do much. Taking both side panels off doesn't stop it, so it isn't those panels vibrating, and I've tried pressing hard on every part of the case to see if I could modify or stop the vibrations, but there was no change.

Thanks,
Dan

 

[Lutfij]

It would help us alot if you could lay out your full systems specs inclusive of your case and the fan's model number if you could as there are a lot of SKU's from both makers. I for one use the Scythe Gentle Typhoons AP-15 and they do present a hum but only due to a small flux in voltage delivery from my fan controller. So that is my follow up question, are you talking about audible vibration from the fans when they work in tandem or are you talking about the rpm's of the fans and the noise that they make? In the latter case, how have you hooked your fans to the system?

You could try this in place of your metal screws...or these anti-vibration gaskets for the fans themselves?