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BabyBalla
(@babyballa)
Guru

http://www.silverstonetek.com/tech/wh_positive.php?area=

interesting.... top should be used as intake vs exhaust

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Posted : 18/11/2010 8:41 pm
Darken1
(@darken1)
Jedi

Interesting 🙂
I know heat rises and i like to exhaust it out of my case as fast as possible, not to crazy about pushing it back down.
Nice find REP

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Posted : 18/11/2010 9:16 pm
BabyBalla
(@babyballa)
Guru

same, it seems to give the best result pushing it back down. I might try that and see. I need dust filters tho...

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Posted : 18/11/2010 9:24 pm
Darken1
(@darken1)
Jedi

Won't hurt to try, i like the idea of keeping dust out. :good:

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Posted : 18/11/2010 9:35 pm
strudinox
(@strudinox)
BOT Admin

I've always used a positive pressure. It really makes a difference when keeping your GPU and PSU cool. 🙂

I've not 5 intake fans and only 2 exhaust.

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Posted : 18/11/2010 10:37 pm
Jester
(@jester)
Member Moderator

@tWkR 47614 wrote:

http://www.silverstonetek.com/tech/wh_positive.php?area=

interesting.... top should be used as intake vs exhaust

I don't like that cooling method used to achieve positive pressure. Heat naturally rises so you want the top fans to exhaust. If you want positive pressure in a standard case, go for good front and side intake, and maybe bottom intake as well. Let the rear and top fans exhaust air.

That article doesn't discuss neutral air pressure which as you can imagine, is formed when you have equal intake and exhaust. A neutral air pressure system has no passive air movement so you might encounter hot spots in your case (heat build-up) with this type of airflow, especially if you have a little amount of fans. This was Bored's problem (member on this site) - his case only had a front and back 120mm fan with equal stats. Heat build up was immense and now his GTX 295 is dying.

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Posted : 19/11/2010 11:16 am
critical
(@critical)
Trusted

idk i always felt like positive pressure is the way to go, with a good cross ventilation. it flows over the cpu and gup and is pushed out the back and any extra hot air flows out the top. i have the HAF 942 and it seems to be affective.

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Posted : 24/01/2011 3:12 pm
clamatowas
(@clamatowas)
Jedi

Positive is with out a doubt better, the air inside of your case can be 40F but if you have no CFM your components are going to get hot and die. With positive your will have the CFM required to remove the heat. After all it is basic physics that are in play. The more particles to adsorb the heat the better off you are, even if they are not super cold. Their is even a formula developed for data centers that you can use to find out how much CFM you require at what temp depending on your power pull

The formula is called the Delta T
(CFM=Volts X amps X 3.414/ 1.08 X temperature rise)

Temperature rise is how hot the air is going into the system vs coming out.

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Posted : 24/01/2011 4:28 pm
strudinox
(@strudinox)
BOT Admin

@clamatowas 57792 wrote:

(CFM=Volts X amps X 3.414/ 1.08 X temperature rise)
.

😐

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Posted : 24/01/2011 5:34 pm
clamatowas
(@clamatowas)
Jedi

YEah find out how many amps system pulls at how many volts and times that together, that will get you your BTU. Times that by 3.14.
Than times 1.08 by the Temperature rise.

Divide the two numbers.

And that will tell you how much CFM you need to cool your system.

You can see me use this on the GEEKBOX EGO review, just so a search for
Airflow/Cooling (Max .25)

Link to review
http://www.gnd-tech.com/main/content/469-GEEK-BOX-EGO-REVIEW

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Posted : 24/01/2011 6:05 pm
Sonex
(@sonex)
Padawan

So negative air flow would be more exhaust fans than intake? And it would make sense that if you have lots of exhaust its pulling all the hot air out as well, there will always be air being pulled into the case so I cant see the ownfall there either

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Posted : 15/04/2011 5:25 pm
Jester
(@jester)
Member Moderator

@Sonex 67138 wrote:

So negative air flow would be more exhaust fans than intake? And it would make sense that if you have lots of exhaust its pulling all the hot air out as well, there will always be air being pulled into the case so I cant see the ownfall there either

Yes negative air pressure is when you have more exhaust fans than intake. The downside is less air is being pulled into the case, and dust can be brought in passively. Most high air flow cases are set up with positive air pressure with intake fans blasting inside of the case, especially toward the GPU area.

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Posted : 15/04/2011 6:03 pm
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