Originally Posted by nleksan
I would disagree and say that static pressure IS quite important for case fans. I would not recommend anything with less than 1.5mmH2O for use as a case fan. When it comes to radiators, static pressure is the most important spec to watch for. Generally speaking I would go with 2-2.5mmH2O for every 10fpi on a radiator.
I kind of agree with you on case fans, particularly the intake fans, the reasoning for this is current case design. Most cases today use the cross section HD bays, this results in easier bay access and drive swapping but reduces the air flow of the intake fan quite a bit. Now this obviously does not cause the issues with back pressure that a radiator causes but it still causes enough obstruction that some back pressure should be expected. The issue is that most high volume fans have very low pressure tolerances and thus can have a huge reduction in their air flow. with very little back pressure required. This means, in theory that a solid, mid range static pressure fan might have lower air flow numbers but could result in higher air flow none the less.
As for the exhaust fan, static pressure is not an issue unless you are passing the exhaust through a radiator.
Also when it comes to high static pressure fans, remember that the high pressure only applies for a fan that is pushing air. The higher static pressure is based on the fans ability to overcome resistance created when the air pillows in front of the fan creating back pressure. The pull configuration, even with a radiator is not faced with a high pressure issue and so the strength of these fans do not come into play. In fact with a radiation if you are going to single fan never put in pull if you can help it but rather push so the fan can do the work.
When you pull through a limited space or a restricted flow area the issues is not back pressure but the fan starving for air. Increases pressure does not help this as the fan has nothing to fight against. This is where volume airflow helps as it can pull harder by creating a larger vacuum to bring in the air.