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How much air in and out?

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Mictlan

Senior OC BOINC User
Joined
Apr 17, 2001
Location
Mexico City, Mexico
I'm planning in installing some new case fans, but I wanted to know how much different can the air (cfm) in must be from the air out?
 

Placid

Senior Member
Joined
Mar 13, 2001
Location
Connecticut
I prefer having more air going out than in fan wise.
I have a 120mm intake and 1 80mm exhaust(blowhole) and the power supply's 80mm exhaust.

My motherboard temp shows room temp + 10f all the time. And my overclocked cpu +1f over the motherboard at idle.
Sorry I dont know the cfm of the fans 2 are sunnon and the other is the power supply.
 
R

robjustice

Guest
You want to keep then close, but always have more going out than in. You DO not what to more in than out, or to pressurize the inside of the case. Pressure has a way of holding the heat closer to the surface. You should try and keep it close, with about 10 to 15 percent more going out.
 

Door Knob

Member
Joined
Feb 9, 2001
Actually the consensus in previose posts has been that youi want a little bit more air comming in than out. The extra heat cause by the extra pressure is nominal and the extra presure keeps the dust out. I'll go see if I can find a link to a good thread about it.
 

Placid

Senior Member
Joined
Mar 13, 2001
Location
Connecticut
Good reading, if your worried about dust bunnys then I guess the positive pressure is for you.
If not then the negative.
A close balance either way.
It seems to me with a negative pressure you would have more cfm of cool air flowing thru the case than with positive as the intake fans would have zero resistance.
Would be a good article for someone to do some testing with.
 

mikren

Registered
Joined
Apr 5, 2001
Let me get this straight...having more air drawn in the case creates less dust bunnies??? How so? Having more fans sucking air in than blowing out would create more dust (logically) no? Your sucking in all dust particals and cig. smoke inside the case which sticks to everything...Doesn't make any sense!
 

rugby

King of Cats Senior
Joined
Feb 2, 2001
Location
Chicago, IL
It makes sense if you have dust covers on your fans then the air going into the case is only going in through the dust cover. If you have lots of fans pulling air out of the case dust will accumulate in every crack and crevice in your case because air is being drawn in from all those little holes. This doesn't happen with more pressure inside the case because air is coming OUT those little holes. I have a ton of air moving through my case and have almost no dust inside. In fact one time my case was actually bowing out because of the pressure. I finally realized my exhaust fan was ALSO blowing air into the case on accident.