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 Post subject: Hardmounted HDD noise and intake airflow
PostPosted: Thu Dec 29, 2011 10:08 pm 
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Joined: Tue Jan 21, 2003 9:59 am
Posts: 163
Location: Malmo, Sweden
I've been thinking lately about how the placement of two HDDs in my Define R3 affect overall noise and airflow. At a basic level, Placing HDDs lower in ther drive bay places the noise farther from the ear but restricts the airflow from the front case fan. Where the "sweet spot" might lie could be rather subjective and a matter of priorities(noise vs airflow). Here we're mainly concerned with silence. It gets more interesting when I try to consider how vibrations are transmitted mechanically(grommets can only go so far) throughout the case, which so far to me has shown to have the largest impact on overall noise.
I've considered some different approaches but either way the proof is in the pudding and I'm merely a layman in these areas. Read on for my results so far.

The drives I have are one WD-GP 1.5GB, 3-platter, very silent. The second drive is a louder 4-platter 3GB WD-GP, this one causes oscillation and proliferation of vibration and seek noise. Also runs hotter.

Here's my current arranangement:
Image

It's a lot better than my previous arrangement acoustically, no oscillation and rather mild "amplification" during heavy seeking. My speculation as to why:
The drive bay gets reinforced at it's structurally weakest/most flexible point at the center where vibrations would more likely be picked up and transferred throughout the case.

That's about it. Any input related to my problem, academic or anecdotal would be appreciated.

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Fractal Design Define R3, Gigabyte Z68XP-UD4, Intel i5-2500k, Thermalright TRUE Rev. C, Seasonic X-560, Samsung 830, WD Green 3TB, Scythe S-Flex 120mm intake, exhaust and CPU @6-700rpm


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 Post subject: Re: Hardmounted HDD noise and intake airflow
PostPosted: Sun Jan 01, 2012 8:45 am 
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Joined: Tue Jan 21, 2003 9:59 am
Posts: 163
Location: Malmo, Sweden
Happy new year, everyone! Some further musings about lower-in-the-drive bay/further-away-from-the-ear vs. obstructed-intake-fan balance. Positive pressure vs negative pressure matters here, doesn't it?

Perhaps something along the lines of:
Negative pressure:
Less of a concern for CPU/GPU if front intake is obstructed. Less airflow for HDDs if mounted farther away from intake fan.
Positive pressure:
HDDs are more likely to receive good airflow either way but CPU/GPU might take a hit if intake is obstructed.

Negative pressure comes out on top with this reasoning as the HDDs we use are usually cooler running low-RPM type.

Could I be getting this right?

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Fractal Design Define R3, Gigabyte Z68XP-UD4, Intel i5-2500k, Thermalright TRUE Rev. C, Seasonic X-560, Samsung 830, WD Green 3TB, Scythe S-Flex 120mm intake, exhaust and CPU @6-700rpm


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 Post subject: Re: Hardmounted HDD noise and intake airflow
PostPosted: Sun Jan 01, 2012 12:59 pm 
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Joined: Mon Jul 16, 2007 2:35 pm
Posts: 808
Location: Greece
I like your approach of strategic drive placement in order to structurally reinforce the hdd cage. You could take it a step further by adding more drives (unused left overs or failed drives).

On the other hand, the wider than usual hdd cage looks like a good candidate for elastic suspension. The first approach is interesting but in the end of the day, elastic suspension is probably the most effective. It should eliminate vibrational noise once and for all. It would also give you more freedom in placing your drives so you could take better advantage of the front fan.

As for airflow, there are reasons to go with positive pressure but hdd cooling is usually not one of them: as long as the drives are behind even a slow moving fan, I don`t see overheating ever becoming a problem. PP can encourage air movement in spots outside the main "zone" of airflow with components relying on passive cooling benefiting the most. The other advantage is dust buildup reduction. Personally, I don`t find it that much harder to clean the interior of my pc compared to cleaning the filters though the ones in the R3 seem quite easily removable.

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 Post subject: Re: Hardmounted HDD noise and intake airflow
PostPosted: Sun Jan 01, 2012 1:14 pm 
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Joined: Sun Sep 05, 2004 1:51 pm
Posts: 685
Location: Gefle, Sweden
If you feel like experimenting further I would give it a go with putting the loud drive upside down (cast metal side up) and tie or prop up the drive to the sled instead of using scews. The regular upside would then rest on the grommets, the hot part of the drive would face upwards and more of the noise would be downwards as well. Although the high pitched noise would simply bounce off the sled surface, it might improve ever so slightly as well. The downside is that cabling might get a bit awkward. With that fan nearby it could even be feasible to have a thin piece of soft foam under the drive, as it would help against high pitch noise.

Apart from when using really hot grahics cards I wouldn't worry about drives getting in the way of airflow. There's enough room for air to get around a couple of drives anyway. For hot cards there's always the bottom vent, which I would otherwise block off on the other hand.

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i5-3570K at 4 GHz Turbo, HR-02 Macho w/o fan, MSI R9 290 Gaming, Fractal Design Define R4, 2 front fans, 1 exhaust. 2 SSD's and a quiet Seagate 4TB (ST4000DM000) HDD, Seasonic P-460FL (no squealing).


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