SPCR

I've got this little niggle on my main which is quite annoying: when the case fan is spinning within a certain RPM range the PC emits a distinct 'whooooo' noise. It is quite loud too! ...more than the rest of the PC anyway. Bump the voltage a little, or turn it a bit down, and it's gone. The funny part is, also accelerating the CPU fan makes it disappear.

Is this cavity resonance, and how can I get rid of it without messing with the fan controller?

Hmmm... how do you get rid of it? I think you've already got the answer

Bump the voltage a little, or turn it a bit down, and it's gone.

Just do it and leave it there, what's the problem?

Other than that, I can see you've already suspended the fans. Maybe changing them to smoother running units would fix the problem. Your solution is cheaper though

I wonder if adding some dense foam blocks to the empty 5 1/4 bays would help? I have a solo, have not heard any noise yet, but I plan on adding blocks anyways. They are available at endpcnoise.com and some other places.

I also took out the tri speed fan and mounted a Noctua silent fan with rubber grommets. SWEET SILENCE

Dave

capecodbackup wrote:I wonder if adding some dense foam blocks to the empty 5 1/4 bays would help?

That could something worth trying. I dug up a formula from this page:

http://hyperphysics.phy-astr.gsu.edu/HB ... ty.html#c3

And it suggests that the blocks -by reducing the volume- should drive the resonant frequency up. Not sure if that would be enough or whether the dampening effect can affect resonance..?

Due to the nature of the sound I don't think it's a mechanical vibration through the case, the noise is just too smooth.

BTW the fan is an S-Flex and is very quiet up until 60% voltage, but the rubber grommets are not that great. OTOH two of the holes on the Solo are just too big for other rubber grommets to fit snugly.

KadazanPL wrote:Just do it and leave it there, what's the problem?

The fan is thermally controlled so to avoid it sitting in that RPM range would require tweaking the transfer curve.

I am hoping my Noctua cooler comes today! Then I will just have to steel my self to take my beloved computer apart