Question about Case Fans..

When installing case fans in the front do you want to pull in the air or blow out the air? When you install the fans in the back do you want the air to blow out or in?

I believe it is, in front you want them to blow in, and in the back you want it to blow out..


Is this correct?

Thanks in advance,
Brian

 

Hey welcome to Major Geeks BrianCharlie and great question. Most fans Suck/Pull air better than they Push/Blow air, and the reason is basic aerodynamics. A fan like a prop in water can "Bite" clean undisturbed material more efficiently than it can push it. So if you have a "Clean Box" and a 600cfm fan sucking air into the box, you should in theory have a slightly larger fan sucking that air out of the box. Hope that Helps

 

Hey there, Brian. BCGray, good answer, but I believe his question was more basic. Correct me if I am wrong, Brian, but you want to know the physics of case cooling in general.

You are correct when you say that the front should intake air and the rear fans should exhaust air. This is to create an air flow throughout the case. That brings us to another question you may have....Where do you place the fans exactly? Remember, hot air rises so you want exhaust fans to be higher and intake fans to be lower, generally speaking. So, the intake fan in the front should be on the lower front of the case pulling air in. There should be some exhaust fans in the upper rear near the processor zone pushing air out. This leads to a final question- How many fans do I need? You need as many as to keep the case cool and promote good airflow, within reason. You want to maintain as close as possible to neutral air flow. Remember, in one way, a case can be described as either positive-pressure or negative-pressure. Positive-pressured cases have a larger intake than exhaust, while it’s the opposite for negative-pressured ones. Too much of either will create competition between both forces and will slow the fans. Too many fans pushing air out will make them compete for air in the case, slowing them while too many pulling air in will force the intake into competition, slowing them. You also force air out of cracks and crevices in the case, or vice versa. Here is a good diagram from another thread.

http://i20.photobucket.com/albums/b213/Ku-sama/Computer Diagrams/sdghghsfg.jpg

Also note that you may have intake fans on the side of the case near the vid card and another direct to the processor. You may also consider a blow hole on the top (remember hot air rises) to help. Try to keep neutral air flow- your fans won't be competing (there is only so much air that can be pumped in or out and fans will slow when air pushes back on them). Also consider obstacles in the way of air flow (such as thick cables). Good luck.