Positive/Negative Airflow?

Blackhawk47 · 28 Mar 2009 at 18:52

Hey guys,

So a quick question here, what does positive/negative airflow actually mean. What is better and how am i suppose to go around getting it right.

I mean how can i tell. So far i think positive is better but is it just to do with fan positions or some how the speed of airflow or what?

Any help is much appreciated.

Cheers

Blackhawk

AtreuS · 28 Mar 2009 at 18:59

From my understanding it means that you ideally want your case to have a higher pressure inside it than the room outside, so forcing the warm air inside to pass out.

If you had only fans sucking air out of the case for example you would creative a negative pressure and so air would be dragged it to the case through joins, holes and so on.

This would drag a lot of dust in at places where you cannot have dust filters.

The ideal situation is to have fans sucking in, behind dust filters, and creating a positive internal pressure so the air seeps OUT through the holes and vents ( and exhaust fans of course ).

The only real ways i could think to test would be to use smoke to follow the air flow, or to check where dust builds up.

willy · 28 Mar 2009 at 19:07

Silverstone Fortress use positive airflow and i noticed when did IBT today, my temp 6c less than my old case

Ace Modder · 28 Mar 2009 at 19:42

positive airflow is having more air sucked into case then blown out.

And visa-versa for negative.

Blackhawk47 · 28 Mar 2009 at 21:05

Alright so at the moment, i have two 120mm intake fans at the front, a 120mm exhaust at the rear and a 200mm on the top for exhaust.

Is there anything you would change there to improve things airflow wise?

EDIT:

LukeTW · 28 Mar 2009 at 21:54

Erm.. not really no

Blackhawk47 · 28 Mar 2009 at 22:27

LukeTW said:
Erm.. not really no

Okay then

I could try and sort cable management out better but i think that will happen when i get a new mobo/hdd which i am just holding out for at the moment.

Diggsy · 28 Mar 2009 at 23:25

Blackhawk47 said:
Alright so at the moment, i have two 120mm intake fans at the front, a 120mm exhaust at the rear and a 200mm on the top for exhaust.

Is there anything you would change there to improve things airflow wise?

You could try reversing the 200mm and have it as an intake, ala Fortress. With 2 120's and the 200 bringing air in and a 120 pushing it out, you should get similar airflow to the Fortress - positive air pressure. At the moment, you have negative air pressure.

Only way to see if it suits your setup is to try running positive. Worth a shot for a couple of minutes effort to reverse the fan.