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Case Airflow


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#1 Kaos

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Posted 12 December 2005 - 05:54 PM

What's the general consensus in terms of airflow in and out of the case? More in than out (positive pressure)? More out than in (negative pressure)? Keep it all about equal?

Just got all my new stuff, went with an Antec P180 case. Looking to order some better fans for it, and just wondering how I should configure it. It's sectioned off with the HD's and PSU in the lower section and everything else in the upper section. The upper section has one 120mm intake and 2 120mm exhaust fans. With the 7800GTX 512mb, that will also exhaust its air directly out the back of the case. I could put some 104CFM Panaflo's all around, or put a 114CFM on the intake and stick with either the stock 79 CFM fans on exhaust or get some 85CFM Panaflo's.

The lower section just has one 120mm in the middle of it pulling air across the drives and pushing it back to and around the power supply. The stock fan there is only 60 CFM, so I'm definitely gonna bump that up to something better.

Any thoughts? Or is it pretty much gonna be all good no matter which way I do it? :)
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#2 Ste

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Posted 12 December 2005 - 05:58 PM

I think the best is one out to every two in.
So I guess positive pressure.

With my case, I have 1 120MM out, 3 80MM in, and 1 120MM in.


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#3 thespin

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Posted 12 December 2005 - 06:01 PM

I don't know of any positive/negative effects to having positive/negative pressure in the case. The goal is to have adequate or better airflow over all parts that need to be cooled. I try to get air moving as fast as possible front to back with a fan or two over memory and the chipset. And I try to avoid conflicting flow. Cable management (try running most of your wires behind the mobo tray) is also important to having good airflow ...

#4 anthony

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Posted 12 December 2005 - 06:04 PM

From my experience, I have always had better temps with negative air preasure.


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#5 romeo55

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Posted 12 December 2005 - 06:23 PM

I always try to have equal airpressure... more air flows faster

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#6 kobalt

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Posted 14 December 2005 - 05:15 PM

I'll tip the balance saying positive, simply cause with negative dust will get in faster in your case trough cracks in CD/DVD drives and that's not good :(
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#7 Savan

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Posted 14 December 2005 - 05:21 PM

I say positive

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#8 danyo64

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Posted 14 December 2005 - 05:24 PM

i say neutral or negative, negative would always be sucking in colder air, but dust could accumulate. neutral would just circulate the air, there wouldnt be a build up of hot air in the case (+ve)

#9 i_lag

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Posted 14 December 2005 - 05:32 PM

i would say, slight negitive, but just make it neatrul..... or w/e just place the fans where u think there will be a build up of hot air(top of case) and where u think the intake would be best situated. positve/negitive/neatrul, not that big of a difference..... but negitive, or neatrul would proform better....

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#10 Ste

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Posted 14 December 2005 - 05:41 PM

i say neutral or negative, negative would always be sucking in colder air, but dust could accumulate. neutral would just circulate the air, there wouldnt be a build up of hot air in the case (+ve)

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Um isn't negative pressure having more air blown out?

Isn't positive pressure having More Air comming in?

I coulda gotten them confused, but I always thought they were that.


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#11 g_bones

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Posted 16 December 2005 - 05:50 PM

Um isn't negative pressure having more air blown out?

Isn't positive pressure having More Air comming in?

I coulda gotten them confused, but I always thought they were that.

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I think he meant that cold air would always be entering because of the negative pressure. In a negative pressure setup, cooler air will enter in at any opening, through cracks, grills, anywhere it can.

For straight out cooling performance, I'd agree that a slightly negative setup would be best. The air that comes in through the cracks help to eliminate hot spots. However, there are definite benefits to having positive pressure. For example, I use fan filters on all intake fans. Having positive pressure ensures that no air enters my case without passing through the filters. All the cracks and grills have air exiting. This is nice in a house with pets, or for anyone who would rather vacuum off the filters every month or so instead of breaking the whole system apart and cleaning with compressed air.

No matter what setup you use, the basics stand true. Get cool air to the hot parts, and then get the hot air out.
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#12 r_target

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Posted 16 December 2005 - 09:39 PM

Just keep the air moving. That's all that matters.
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