Another question is the air pressure inside the chassis,
I am planning to build up a slightly positive pressure inside the chassis so that some air can be exhausted from the PCI slots holes.
![](http://lian-li.com/v2/tw/product/upload/image/pc-b25s/b25s-06.jpg)
Or instead I should just avoid +pressure?
Negative pressure will end up sucking dust from the PCI slots.