Noise reduction for my SC-750A

[HitoZen]

I'm pursuing a small project on quieting the noise generated by my computer.

I have a SUPERMICRO SC-750A case, with about 9 exhaust/intake fans installed. The freakin thing is as loud as a m0f0. I found a site that explains the usage of carpet bedding to absorb the noise.

The problem is, I can't get my hands on any of that material. You guy know of any cheap substitutes?? The material would most defintely have to be high density foam/polymer. Right now I can think of those eggcrate bed things but that's about it.

Thx!

[tophenhaw]

dynamat

[HitoZen]

Originally posted by tophenhaw
dynamat

damn that dynamat's expensive. i need a CHEAP solution!! hehe but thx anyway.

i'm now thinking about a foam-plywood-foam combo. dunno.

[Startide]

Check out the prices at crutchfield.com

Anyways, there are multiple options for quieting the thing down similar to your automobile. You can

• Stick on a sheet of sound deadener. Typically this is dynamat although there are copycats. Apply a layer of dynamat or adhesive roofing asphaltum sheets (similar to dynamat but not as cosmetic or nice)
• Spray on some sound deadener substance. Imagine something similar to that scrubbing bubbles bathroom cleaner but the foam dries hard and deadens the panels. This is particularly useful for odd-shaped objects that you cannot wrap dynamat around.
• Attach a sound-deadener applique. 3M has pioneered in this field and they are remarkably effective. Imagine a sheet of thick aluminum alloy (proprietary) that is coated on one side with a sticky adhesive whose thickness and elasticity is proprietary.

As for the "carpet bedding", a good description is a one or two foot square piece of low-pile industrial carpet. One side is coated with a black rubbery asphalt-like material that has a sticky adhesive. If you pull the non-stick wrapper off, you can then press this thing up to something and it will stick pretty well. I don't think it works as well as dynamat and it also eats up your space.

You can cut the noise down if you use isolated mounted fans. I've seen one elaborate case by Epson (an industrial instrument unit for workplace) that had the fan mounted to metal arms full of s-curves so that the sound would not couple directly to the case.

[Startide]

HERE IS THE LEAST-INVASIVE ENGINEERING SOLUTION I COULD THINK OF THAT MEETS YOUR REQUIREMENTS FOR COST AND EFFECTIVENESS.

Isolating each fan body so that it doesn't directly contact the metal case is the best first way to reduce noise. The vibration of each fan resonates with the metal case to increase the apparant noise.

What about getting some rubber grommets. Don't line the bolt hole with the grommet as that means you will have to enlarge the hole to make the grommet fit. INSTEAD, use the soft rubber grommet like a washer. Put this soft rubber "washer" in between the fan body and the case for each of the four bolts.

The rubber grommets are cheap and you can quickly put them on several of the fans provided that the bolts are long enough to accommodate the extra thickness of the grommets.

Criteria:

1. Grommets must not be too thick. You can cut grommets sideways and that will yield two convenient halves that you can then use on two bolt holes. Saves a little money.

2. Use a lock washer on the nut side. This is needed due to the extra play of the grommet.

Design Caveat:

1. If the extra play increases the risk that the nut can loosen over time and fall inside the case onto the motherboard and short something out and you live in Chicago and the shorted motherboard catches on fire and causes the 2nd "oleary's motherboard fire" then don't try this approach of isolating the fans from the case. That is why industry has these $50 isolation mounts for fans. Ugh.