What can I do about this noise?

viivo

[H]ard|Gawd
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I've been trying different airflow configurations in my Corsair 700d. Since I had to mount my CPU fan on top of the heatsink blowing down, I couldn't leave it as it was with just one intake on the bottom and three blowing out (1 rear, two top.)

Anyway, the problem is that with either the rear 140mm blowing in, or one 120mm on top blowing in, the noise is doubled compared to the normal flow. When I put pressure on top near the fan blowing in, the noise stops. It doesn't sound like rattling, it's just air blowing but when I take the fan out and hold it it's completely silent.

All my fans are controlled, and even at 40 and 50% the noise is there.

Any suggestions would be appreciated.
 

fochkoph

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Mind posting pictures? I'm wondering why you would have to mount the heatsink blowing downwards which goes against the intended airflow of that particular case. Why not flip the fan around and have it suck air through the heatsink blowing the air upwards into the top exhaust fans? Nothing wrong with one intake and three exhaust since most cases function with a negative airflow (more air being sucked out than in). Personally, I'd keep it the way it was since...

a) Having intake and exhaust fans as high up as they are in the 700D and next to each other in that manner makes little sense because the air going in is immediately sucked back out doing virtually nothing.

b) If the noise wasn't there to begin with, the three exhaust to single intake should work fine as the 700D has plenty of vents to pull air through and into the case while eliminating the noise problem. :)
 

viivo

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I mounted it on top because the NB cooler only allows the heatsink to be mounted one way and with only one fan (I was using push-pull, but the constant 75+c temp of the NB was irritating me.)

Pictures:

140mm blowing in, fan on NB pulling, CPU fan pushing.
http://img.photobucket.com/albums/v303/Sintek/IMG_1450.jpg. Damn dust really shows up with a flash. Wish those fan filters would hurry up.

The two culprits on top, thinking about removing the forward one since temps don't move at all when it's off. http://img.photobucket.com/albums/v303/Sintek/IMG_1452.jpg

My thought was this: in through rear (har har,) through cpu HSF, through NB HSF and out and up through the top. I guess it works but I wasn't counting on the extra noise.
 
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fochkoph

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Have you tried rotating the NB heatsink? Or is that not possible. If it is then you should definitely try is since you can mount the fan on the opposite side of the CPU heatsink so it's blowing upwards and through the heatsink with the NB fan blowing upwards as well. Just noticed it looks like you're sacrificing the top PCIe slot for the NB heatsink too...[H]ardcore!

If you can just remove the fan entirely without impacting temperatures you might as well. Never hurts to cut down on one more moving part that makes noise. You can also invest in some silicone gaskets that fit between the fan and case that might possibly eliminate any noise, but since you said it isn't rattling then that might be a bit far fetched. :p
 

Nuzzles

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The noise is coming from the air being sucked through the honeycomb grating. I'm not really sure why it does it for the intake and not outtake, but it happens. I've got a real budget solution going on at the moment with my rear fan being an intake (running my CPU underclocked passively atm) using a portion of this nonslip pad which has a lot of holes in it over the grating on the outside of the case. Cuts down the noise a TON.
 
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viivo

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The noise is coming from the air being sucked through the honeycomb grating. I'm not really sure why it does it for the intake and not outtake, but it happens. I've got a real budget solution going on at the moment with my rear fan being an intake (running my CPU underclocked passively atm) using a portion of this nonslip pad which has a lot of holes in it over the grating on the outside of the case. Cuts down the noise a TON.

Do you have any pictures of what that looks like?

I made a trip to Menards yesterday to look for any products that might help me in silencing my case. They have no nylon screws, or any non-metal screws, no rubber washers of any size (surprised me) and absolutely no sound dampening material. For a hardware store, Menards sucks big ones. Wish we had a Lowe's or Home Depot here.
 

Nuzzles

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It's just rolls of stuff that look like this:
sh0c1.jpg


I think that putting anything that is a bit airy over it will help cut down the noise. On my CM690 II if I take the dust filter off the bottom of the case the fan will instantly become extremely noisy. Main reason I'm using this is just because it was lying around the house.

Ideally it'd be best to just cut the honeycomb out, but i don't plan on having it set up like this for much longer and it should be back to exhausting soon (that and i can't find my dremel or any snippers for the job)

Edit:you could try mounting the fan on the outside blowing in and routing the cable through one of the watercooling tube holes. not the most elegant solution but i'm pretty sure it would work and it would save you from cutting into your case or buying anything.
 
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