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 Post subject: The Ultimate HD Sandwich (well, maybe)
PostPosted: Sat Nov 02, 2002 12:02 pm 
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Hello, new to the forums, howyadoin, nice to meet you. :)

I've been working on a quieter PC for a while. I'm to the point where the loudest things in my case are my Western Digital SE 100GB drives (two of them in a RAID 1) and the whine is killing me. It isn't feasible to replace them, so I want to sandwich 'em. I have a few considerations that make me want to create a 'better sandwich' than the usual:

1) My HDs see a LOT of activity - quite a bit of Photoshop work with big files - so cooling is important.

2) My Coolermaster case has 2 80mm fans blowing over the HDs now, and the drive cage is not removable. I have to make the sandwich fit in that space, and with the extra mass of the sandwich plages blocking airflow I think my cooling may be a bit *worse* with the sandwich than it would be with the drives mounted in that cage with the fans blowing right over them.

3) If I sandwich then they'll have to sit on their sides to fit in that 'cage' area and still be near fans.

So, I fired up Illustrator, and dreamed up the 'ultimate HD sandwich'. I probably can't afford to get this made, but I wanted to express the idea and get some feedback. Here it is:

Image

Now, after thinking about it, I could probably just get the 3/8" aluminum blocks (four for top/bottom, four for side-sinks) cut and then fasten some thin aluminum U-channel on with thermal epoxy (I have plenty left from my two Zalman chipset coolers). I should probably have the machine shop polish them too, so I have the best contact for the glue-on U-channels.

So, how does this look? (Is it complete overkill? :D) Any ideas, or anything I might improve upon?

schnee


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 Post subject:
PostPosted: Sat Nov 02, 2002 12:41 pm 
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Welcome to SPCR! Nice design artwork, but it IS overkill and may not work that well.

1) mechanical decoupling is the single most effective way to reduce drive noise. Try it by temporarily removing the drives from the cage & resting both on soft foam -- even one on top of the other. You will be amazed. But it may not get rid of the whine.

2) sidesinks by themselves are plenty enough to cool the drives if you have airflow across them anyway, and if they are longer than the drives.

3) the aluminum plates are not that effective at noise reduction without decoupling; a layer of cork or similar material between the plates and the drive will definitely provide more noise reduction, especially of the highs

4) your best bet might be to carve up a block of foam so that each drive is nestled in the foam, with side sinks sticking out beyond the foam. The drive would be completely encased in foam, with all openings for cables well covered up. The foam does two things --

-- decouple the drive from the case
-- absorb freq higher than ~500Hz

Each foam block could occupy half the sampe you have room for; the 2 together would be wedged together for simple friction-fit. (Sounds like you don't move the system anyway, so...)

the side sinks must protrude at least a couple of inches. They're basically "wicking" the heat to the ourside where it can be tranferred into the air. You could expand the amount of exposed heat radiating surface by connecting the exposed sidesinks with a piece of heatsink material

5) the grooved/ridged/finned aluminum sheeting you're thinking of is used widely in car amps. You might be able to find a burnt-out power amp from a car audio dealer for cheap and adapt its heatsinks for your purpose.

This will be a whole lot cheaper to try. If the temps get higher than you're comfortable with, you can always go back... but probably won't be able to because the drive noise wil REALLy kill you after living with its absence for any length of time ;)


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 Post subject:
PostPosted: Sat Nov 02, 2002 2:21 pm 
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RE: 'mechanical decoupling is the single most effective way to reduce drive noise'
I wasn't clear enough. These drives would be sitting on the bottom of my case, on top of a layer of Magic Fleece that lines my case.

RE: 'sidesinks by themselves are plenty enough to cool the drives if you have airflow across them anyway, and if they are longer than the drives'
Any links to good 'sidesink' stock online? I'm going to Home Depot anyway today, I'll have a look there but I doubt I'll find anything of use...

RE: 'a layer of cork or similar material between the plates and the drive'
So the top and bottom plates would no longer act as heatsinks - more like insulators... so in actuality I wouldn't need more than three I actually have some extra Dynamat left over... maybe a layer of that on each plate would be good, and stuff foam on the front to kill the noise shunting out that way.

RE: 'each drive is nestled in the foam'
I keep seeing recommendations for 'foam', but what specific kind? Where would I go to get it?

RE: 'You might be able to find a burnt-out power amp from a car audio dealer for cheap'
ooOOooo, good idea.

Thanks for the detailed and considered reply.


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PostPosted: Sat Nov 02, 2002 2:32 pm 
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The article on sidesinked drives is in the main site under mods & proj. Effective passive HDD cooling.


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 Post subject:
PostPosted: Sun Nov 03, 2002 12:22 pm 
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Any thoughts on how well a copper sandwich would work?

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 Post subject:
PostPosted: Sun Nov 03, 2002 12:30 pm 
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Quote:
I keep seeing recommendations for 'foam', but what specific kind? Where would I go to get it?
almost any kind is worth a try. Mattress/foam shops have all kinds. You might check to make sure it isn't conductive, but generally they're not.

copper -- never tried it. Hard to work as it is a lot denser & harder than aluminum.


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PostPosted: Sun Nov 03, 2002 10:21 pm 
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A note as far as sound transmission coefficients goes is that lighter and stiffer materials will transmit sound more effectively. Lead is highly-effective at stopping sound since it won't re-radiate very much at all. Steel is also good, copper would also be good. Aluminum isn't as ideal, although it probably does a reasonable job.

For the sandwich material, I'd suggest something with a high absorption coefficient, such as fiberglass. Fiberglass ceiling panels are dirt cheap, and will absorb on the order of 90-95% of the sound reflecting within the enclosure-- it's highly effective. Cork has an absorption coefficient of only about 10-15%, so I wouldn't recommend that. Foams vary highly depending on the type.


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 Post subject:
PostPosted: Wed Nov 06, 2002 4:22 am 
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"3) the aluminum plates are not that effective at noise reduction without decoupling; a layer of cork or similar material between the plates and the drive will definitely provide more noise reduction, especially of the highs"

Aluminum mostly reflects sound, but it also absorbs it very well (since it is heavy) if you build an airtight isolation.

I wouldn't recommend any foam or corc etc. Instead you should use cement. It's cheap and effective and easy to use (just add water and sand...)

Instructions:
1. connect some big heatsink to the top of upper hard disk and bottom of lower hard disk using arctic silver adhesive

2. connect any ide and power cables to hdd's

3. use a thick layer of cement to make an airtight sound isolation for hdd's.


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PostPosted: Wed Nov 06, 2002 4:50 am 
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Seems kind of permanent, doesn't it?

I'm only talking for me now, but I'd like to be able to remove cables, take the hd out etc. without having to hammer my way through a layer of cement to be able to do so...

If you use fiberglass Melchior, where would be the ideal place to place it?


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 Post subject:
PostPosted: Wed Nov 06, 2002 5:10 am 
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cement would be a bit heavy as well wouldn't it? u'd have fun carrying the computer to something like a LAN :).... also one thing as well Artic Silver Thermal Expoxy is known to be a *lil* electrically conductive as well u'd better go with artic alumina expoxy, it's a ceramic compound so not electrically condutive...........
Cement sounds like a interesting way to do it though

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 Post subject:
PostPosted: Wed Nov 06, 2002 4:46 pm 
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Several things should go into a drive-isolation design. An important consideration is that the metal will not absorb much/any sound itself-- rather, the sound will reflect within the drive enclosure (the sandwich plates). The purpose of the foam/fiberglass within the sandwich is to reduce the intensity of those reflections and thereby to minimize the escaping noise.

Between the sandwich plates and the drive you'll get some harmonics that can build up-- it's a function of the distance between the plates and the drive. Since you don't want to hear the drive, the best thing to do is to maximize that distance to bring the harmonics down to lower frequencies, where the human ear doesn't recognize sound as effectively. A couple inches of space would be ideal, but the distance should be at least 3/4". I think 3/4" fiberglass ceiling/wall panels are readily available from Revy/Home Depot for a couple bucks and they'd do the trick handily. If you can use the fiberglass panels to decouple the harddrive from the side plates, then it *could* end up even quieter than if it were only decoupled from the case.

Since fiberglass is a good insulator, make sure the drive has adequate cooling-- the cooling fins MikeC suggested in his "passive harddrive cooling" article are ingenious. I've decoupled my Barracuda IV, placed it in the top of my case (rather than the bottom where it was previously located), and attached some long sinde fins to it, and it runs 2-3 *C cooler than it did previously.

Good luck!


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 Post subject:
PostPosted: Thu Nov 14, 2002 2:40 pm 
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Uh, I think that's a NO to cement for me. :D

Ok, I think I have a bit of a new plan then.

1) Steel 1/4" plates with a layer of Dynamat between the HDs and the plates, bolted on around each HD for a 'sandwich'.
2) Dense rubber on the front and back of the sandwiches to kill more sound.
3) Aluminum U-channel approx. 1-1/2" longer than the drives bolted to the sides to provide cooling.

If it works out as planned, these will be placed vertically in front of the 80mm fans in my Coolermaster. If not, I'll have a pair of WD100 SE drives for sale, and will replace them with Barracuda 80-120Gb drives. :D


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