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air pressure

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W

William

Guest
not sure, but i read this somewhere on the forum to keep more air coming in your case than out by a little bit to create a slight positive pressure in your case. Is this true. If so, then why?
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
That is correct. Two reasons that come to mind are:
Don't forget the PSU needs air through it to cool itself and with a little positive pressure, you're less likely to drwa dust in through all the cracks and crevices on your case (like CD-RW, floppy, etc). It's just good practice.

Hoot
 
K

Kryten

Guest
Hoot (Apr 08, 2001 08:15 p.m.):
That is correct. Two reasons that come to mind are:
Don't forget the PSU needs air through it to cool itself and with a little positive pressure, you're less likely to drwa dust in through all the cracks and crevices on your case (like CD-RW, floppy, etc). It's just good practice.

Hoot

Not wanting to rain on anyones parade but won't having a positive pressure create heat of it's own, I don't know myself I'm just asking because I'm trying to add fans to my case.
How would you feel about neutral?
 

Spike

Registered
Joined
Mar 20, 2001
Newby2OC (Apr 08, 2001 09:51 p.m.):
Hoot (Apr 08, 2001 08:15 p.m.):
That is correct. Two reasons that come to mind are:
Don't forget the PSU needs air through it to cool itself and with a little positive pressure, you're less likely to drwa dust in through all the cracks and crevices on your case (like CD-RW, floppy, etc). It's just good practice.

Hoot

Not wanting to rain on anyones parade but won't having a positive pressure create heat of it's own, I don't know myself I'm just asking because I'm trying to add fans to my case.
How would you feel about neutral?

Positive air pressure (more air in than out) will not, in and of itself, create heat. What it does do though is allow heat pockets to form since some of the excess fresh air will be exhausted instead of already heated air.

What you should try for is a slight negative pressure. Two case fans (one in and one out) of the same rating plus the existing P/S fan will accomplish this.

The air flow is also important. Good card positioning as well as cable dressing and positioning can give you several oC (depending on how bad things are when you start).
 

DocClock aka MadClocker

Senior Member
Joined
Dec 19, 2000
Location
Stockton Cal, USA, Earth
All I know is when I lite a cig, and blow it in the direction of my comp, it either sucks it in through front bottom, or through the blowhole I put in the side of my case....but whichever way it goes in...it only comes out by way of the power supply, and it comes out in a hurry...and of course the smoke has expanded by then, and makes a big cloud kinda cool to watch, but I won't do it just to watch...I ruin enough stuff with nasty cig smoke 'round here...like my lungs
 
OP
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William

Guest
ok, so i guess it doesn't matter too much then. i see both sides of it, but i guess i will have more out than in when all is said and done, caus the psu fan will be exausting.

4 120mm 131cfm fans
4 80mm 43cfm fans

Gonna be pushin some air in that supermicro sc760a.
 

Fink

Member
Joined
Dec 18, 2000
My personal belief is that you should have more air coming IN (positive case pressure). This prevents dust from seeping in the CD-ROM bay, cracks ect...

The heat caused by the very slight positive pressure will be absolutely negligable and is nothing to be concerned about.
 

Door Knob

Member
Joined
Feb 9, 2001
Fink (Apr 09, 2001 06:00 p.m.):
My personal belief is that you should have more air coming IN (positive case pressure). This prevents dust from seeping in the CD-ROM bay, cracks ect...

The heat caused by the very slight positive pressure will be absolutely negligable and is nothing to be concerned about.

My same thoughts completely. Just another opinion for you.
 

Pat

Member
Joined
Jan 22, 2001
Location
Near St. Louis
Had a conservation with 2cooltek & he stated that I need a slight overppresure vs underpresure or balanced airflow.

Pat
 

dimmreaper

Senior Member
Joined
Dec 16, 2000
Location
home
I'm with Hoot, Fink, and Colin, less dust.

I'm thinking of throwing together a home brewed plexiglass case, I'm going with 3 filtered 120mm intakes, 2 120mm exhasts, and I think an Enermax PSU upside-down drawing in fresh air through the top of the case and blowing hot air out the back.