Based on comments in another thread, I now have a question about the ideal way to set up airflow through a case. It seems that there are two camps in this debate -- those that think the air pressure in the case should be positive, and those that think it should be negative. For the sake of clarification, I'll define what I think each of those terms mean:
Positive - there is more fresh air coming into the case than there is hot air exiting the case. Basically, the CFM from intake fans exceeds the CFM from exhaust fans.
Negative - there is more air exiting the case via exhaust fans than fresh air entering the case via intake fans and vents. The CFM for exhaust fans exceeds the CFM from intake fans.
Now I know that very few of us have taken the time to run silicon caulking on all the seams of our computers to make them completely air tight, so there is more involved here than just the fan CFM -- positive pressure cases won't explode over a period of time and negative pressure cases won't implode. Also, the direction of airflow within a case has a lot to do with the effectiveness of the cooling, but let's ignore that for now.
The real question is this, I suppose. Is it better to pull air through the system or to push it? Or does it not really matter? Anyone have links to some good testing on this, or some empirical data to back up theories?
EDIT: I turned this into a poll with a slightly different flavor. Balancing a system's airflow exactly is probably impossible, so when designing your fan setup, should you make it more negative, or more positive?
Positive - there is more fresh air coming into the case than there is hot air exiting the case. Basically, the CFM from intake fans exceeds the CFM from exhaust fans.
Negative - there is more air exiting the case via exhaust fans than fresh air entering the case via intake fans and vents. The CFM for exhaust fans exceeds the CFM from intake fans.
Now I know that very few of us have taken the time to run silicon caulking on all the seams of our computers to make them completely air tight, so there is more involved here than just the fan CFM -- positive pressure cases won't explode over a period of time and negative pressure cases won't implode. Also, the direction of airflow within a case has a lot to do with the effectiveness of the cooling, but let's ignore that for now.
The real question is this, I suppose. Is it better to pull air through the system or to push it? Or does it not really matter? Anyone have links to some good testing on this, or some empirical data to back up theories?
EDIT: I turned this into a poll with a slightly different flavor. Balancing a system's airflow exactly is probably impossible, so when designing your fan setup, should you make it more negative, or more positive?