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Negative, neutral or positive air pressure

post #1 of 18
Thread Starter 
im looking at completely fanning out my case so i am getting 2 new fans a a H50 to do it

ive got 2 fan bays at the front 1 at the side and will mod the top of my case for 2x 140mm two-cool fans

im just wondering if it is good to have all the fans blowing into the case or all facing to the back or all facing out

p.s the room that the computers in is usually at 25c
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post #2 of 18
This works best for me..

[ATTACH]191379[/ATTACH]
post #3 of 18
Thread Starter 
so thats a neutral air pressure

the back of the PC is against a wall as well
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post #4 of 18
positive pressure is more in than out. negative pressure is more out than in. neutral is the same in and out.

You need space between the back of your case and the wall. If there's nothing you can do about it, get a very high cfm fan for the rear (the higher the better)
post #5 of 18
Depends on the case, but i like slightly negative pressure.
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post #6 of 18
Quote:
Originally Posted by LuKrype;12087291 
so thats a neutral air pressure

the back of the PC is against a wall as well

Wouldn't that be positive pressure? He has quite a bit more air being forced in than pulled out, thus the pressure inside the case is greater than that of the environment surrounding it.

Or am I crazy?
post #7 of 18
Thread Starter 
Quote:
Originally Posted by EfemaN;12087320 
Wouldn't that be positive pressure? He has quite a bit more air being forced in than pulled out, thus the pressure inside the case is greater than that of the environment surrounding it.

Or am I crazy?

slightly positive im sure
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post #8 of 18
Thread Starter 
Quote:
Originally Posted by tw33k;12087309 
positive pressure is more in than out. negative pressure is more out than in. neutral is the same in and out.

You need space between the back of your case and the wall. If there's nothing you can do about it, get a very high cfm fan for the rear (the higher the better)

its not RIGHT against the wall it has something line20cm clearence but it's under a table
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post #9 of 18
My set up is ++++. I've only got a 120mm UK 3000 as exhaust. Everything else is intake (including 4 more UKs)
Quote:
Originally Posted by LuKrype;12087334 
its not RIGHT against the wall it has something line20cm clearence but it's under a table

As long as there's room around the case you'll be right. Yours sounds similar to mine
post #10 of 18
My favourite is (slightly) positive pressure (more air going in than out, provided by fans). Why?

Well, I have dust filters on my intake fans. That means that the air going through them will (hopefully) be relatively dust free. That means that hopefully air will be expelled from the excess mesh I have on the case, and ought to keep more dust out.

Conversely, were you using a negative pressure on your case AND had meshed areas, I assume that there would be more air being drawn in through there, and over a few months, the dust buildup would be marginally higher than otherwise.

Is there a huge difference? Not really. It's all down to personal preference.
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