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 Post subject: Positive and negative air pressure
PostPosted: Sun Apr 22, 2012 9:07 am 
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Joined: Mon Mar 05, 2012 1:00 pm
Posts: 182
I also posted this here, but decided to make a new topic to try to ameliorate the nature of a semi-dead forum and many people are too annoyed the click on old topics....

It is a different topic anyway....
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I just learned something today and perhaps you will too since no one mentioned it before.

There actually exists positive and negative air pressure in PC cases.

Positive pressure is created when there are more intake fans than exhaust fans so what this positive pressure does is it pushes the air outside the case.
Negative pressure is created when there are more exhaust fans than intake fans so what this negative pressure does is it sucks the air from outside into the case.

Obviously positive air pressure is better because not only does it push the hot air outside it also doesn't suck all the dust like negative does.

So, I was thinking, since Fractal Design Define R3 only has a fan controller for 3 fans wouldn't it be better to just put one extra intake fan at the bottom thus creating positive air pressure?

Does this sound good in practice as it does in my head? :roll:

Also I see that R3 in its specs has a fan controller, but where is it? Carbide has a fan controller outside just where the power button is, but I can't see such thing anywhere on R3, is it in a box inside the case which you then mount into an optical drive bay or something?


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 Post subject: Re: Positive and negative air pressure
PostPosted: Sun Apr 22, 2012 11:53 am 
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The fan controller is not integrated in the case itself but instead a fan controller placed in one of the PCI slots. It is therefore possible to use the controller in any other computer systems.

The guys over at Bit-tech has actually tried to figure which fan positions and number of fans that are most efficient:
http://www.bit-tech.net/hardware/2012/0 ... igation/10

Bottom, front and rear fan is, sadly, not the most efficient fan setup in terms of thermal performance, but it should easily be fine, depending on your hardware.

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 Post subject: Re: Positive and negative air pressure
PostPosted: Sun Apr 22, 2012 12:52 pm 
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Posts: 182
kuzzia wrote:
The fan controller is not integrated in the case itself but instead a fan controller placed in one of the PCI slots. It is therefore possible to use the controller in any other computer systems.


I don't understand what this means.
How do you control the fans, is there a button on the back, where this card in PCI slot is?
Do you understand that when I see words like "fan controller" I see the meaning of something like a switch with which you turn the lights on in a room but instead of a switch it's a nob that you turn thus increasing/decreasing the light intensity?


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 Post subject: Re: Positive and negative air pressure
PostPosted: Sun Apr 22, 2012 12:56 pm 
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Joined: Fri Aug 05, 2005 3:29 am
Posts: 1067
Location: UK
It looks like this

Image


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 Post subject: Re: Positive and negative air pressure
PostPosted: Sun Apr 22, 2012 1:01 pm 
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Joined: Mon Mar 05, 2012 1:00 pm
Posts: 182
OK, so it's a nob stupidly placed on the back instead on the front...just say so.

as for this:

Quote:
1. The amount of venting in your case can have a huge impact on cooling, particularly around the CPU area. If you have fan mounts here that are blocked up, unblock them.

2. Generally, all other things being equal, it’s better to get hot air out of your case than to pump cool air in, particularly when it comes to CPU cooling.

3. If you have a roof mount that’s located nearer the front of the case than the CPU cooler, leave it open. Fitting a fan here only causes problems.

4. If you have one, two or three fans in your case, the side panel intake mount is the most important. Fill this first, followed by the rear exhaust mount, followed by the roof exhaust mount.

5. Bear in mind the fact that fans have an effect on each other and use this to your advantage. For this to work though they need to be close enough to interact - a side intake works better with a rear exhaust than a front intake does for this reason.

6. With four or more fans, concentrate on traditional front to back cooling and creating one strong, continuous air flow. Fill the front intakes and the roof and rear exhausts first.

7. More fans does mean more cooling, but expect diminishing returns when going above three or four fans.



So, in R3 case this means I should put 1 intake fan on the side or one exhaust on the rear thus creating negative air pressure?
If anyone knows of Linus on youtube he says that positive air pressure is better.
I'm definitely going with only one extra fan since this case has fan controller for 3 fans.

Also this list perfectly describes why Corsair Carbide 500R has far superior cooling, it has huge fan on the side and the rest 3 are front and rear.


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 Post subject: Re: Positive and negative air pressure
PostPosted: Sun Apr 22, 2012 1:17 pm 
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Joined: Tue Sep 07, 2004 11:03 am
Posts: 1128
Location: Europe
Mettyx wrote:
I just learned something today and perhaps you will too since no one mentioned it before.


This forum has a lot of info that can be found with the search function;1483 matches on the terms positive and pressure.


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 Post subject: Re: Positive and negative air pressure
PostPosted: Sun Apr 22, 2012 1:21 pm 
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Joined: Mon Mar 05, 2012 1:00 pm
Posts: 182
Meh, I stopped bothering with forum searches since almost all searches on gaming forums never work, not even the slightest.
Surely you must have noticed this yourselves.

Anyway, seeing that 7 point list was worth making this topic.


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 Post subject: Re: Positive and negative air pressure
PostPosted: Sun Apr 22, 2012 6:14 pm 
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Joined: Mon Mar 05, 2012 1:00 pm
Posts: 182
Do you think just one side 140 mm scythe slipstream fan would noticeably affect the noise level?


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 Post subject: Re: Positive and negative air pressure
PostPosted: Sun Apr 22, 2012 7:59 pm 
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Joined: Thu Feb 04, 2010 6:06 pm
Posts: 3395
Location: US
Quote:
1. The amount of venting in your case can have a huge impact on cooling, particularly around the CPU area. If you have fan mounts here that are blocked up, unblock them.

2. Generally, all other things being equal, it’s better to get hot air out of your case than to pump cool air in, particularly when it comes to CPU cooling.

3. If you have a roof mount that’s located nearer the front of the case than the CPU cooler, leave it open. Fitting a fan here only causes problems.

4. If you have one, two or three fans in your case, the side panel intake mount is the most important. Fill this first, followed by the rear exhaust mount, followed by the roof exhaust mount.

5. Bear in mind the fact that fans have an effect on each other and use this to your advantage. For this to work though they need to be close enough to interact - a side intake works better with a rear exhaust than a front intake does for this reason.

6. With four or more fans, concentrate on traditional front to back cooling and creating one strong, continuous air flow. Fill the front intakes and the roof and rear exhausts first.

7. More fans does mean more cooling, but expect diminishing returns when going above three or four fans.
Much of this... makes little sense to me as general rules. "when going above three or four fans".... what is that about? I think these are rules for teenagers stuffing a case with fans.

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 Post subject: Re: Positive and negative air pressure
PostPosted: Sun May 13, 2012 2:22 am 
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Joined: Mon May 16, 2011 11:23 am
Posts: 581
Location: Germany
Still looking for videos? Kind of mtv-generation i might not be familiar with.

Every one can state something in a video of some sort, not bothering even to explain the testing method used. Whereas serious reviews are always a combination of video and data, explaining testing methods used and pointing to error margins and other caveats.

Blindly trusting not so serious "reviews" leads to the wrong conclusion.

Positive pressure isn't always better. It depends on the case and some other factors.

Finally, as we are interested in silent pc, pos. pressure isn't necessarily the quietest way for every case.


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 Post subject: Re: Positive and negative air pressure
PostPosted: Mon May 14, 2012 6:54 am 
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Joined: Sun Jul 10, 2011 1:56 pm
Posts: 229
Location: UK/Eire
I would tend to agree positive pressure is not always the way to go.
I remember watching some youtube video with a guy bitterly complaining about an Antec Sonata and the negative pressure. The Sonata isn't the best for airflow only because it has relatively few front air intake areas, not because it didn't have a lot of fans at the front.
And it's not exacly your first choice for an overclockers pc case either!

Case design can make a big difference


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 Post subject: Re: Positive and negative air pressure
PostPosted: Fri Jul 27, 2012 9:12 pm 
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Joined: Fri Jul 27, 2012 9:08 pm
Posts: 1
Nice post. I like it. Thanks for sharing these information. Keep it up. :) :lol:

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