Advice on home made case

[albert]

Hi all, only my second post.

I’m going to start building my own case next week. I’m looking for a bit of advice about air intakes.

Obviously I want the intake to be as unrestricted as possible while still blocking noise getting out. I’m planning to build the case from MDF and model it on a P180 design. I thought I’d put two sheets of MDF at the front. One on the inside with holes cut for air to get into the upper and lower chambers. Then a second outer sheet that’s solid. I then plan to leave the bottom of the case open between these two sheets so that air can get in. (It will be on feet and standing on carpet). The case is going to have to be fairly wide because I’ve got a ninja to put in it.

So, questions. What sort of area does the opening at the bottom need to have to get adequate airflow? Is there a way to calculate this?

Do you think it’s worth putting any kind of padding to absorb sound on the inside of the outer front panel?

[Bluefront]

There's really no way to know in advance how big to make air passages....because it depends on the brand of fan, the amount of airflow, the air-path itself, etc. From a noise view-point, a bigger airflow path is better. And it helps to line air channels with acoustic dampening foam.

IMHO....the total area of the intake should be at least 1.5x the area of one medium speed fan. More is better in this case.....

[Bluefront]

forum screw-up.

[IsaacKuo]

Roughly speaking, airflow is bottlenecked by the cross section of minimum area. A good rule of thumb is that you want at least as much total intake area as the total exhaust area. Most computer cases fail to follow this rule of thumb, and as a result the intake is too restrictive. The P180 has inadequate intake area--the total exhaust are is roughly equal to 3 120mm fans, while the total intake area is much less even with the grills removed.

My usual solution to the problem is to put no intakes in the front at all. I prefer all intakes and exhausts in the rear.

[albert]

My usual solution to the problem is to put no intakes in the front at all. I prefer all intakes and exhausts in the rear.

But doesn't that mean little air flowing over the components at the front?

[IsaacKuo]

I generally use a "U-turn" airflow plan where air first travels forward before bending upward and then ultimately back out the rear. The obvious way to accomplish this is with a partial internal partition.

A sufficiently large video card can act as this partition, but few video cards fill out the full width of a case. Therefore, I use a partition resting on top of the video card that blocks the full width of the case. This forces air to first go forward to the front of the case before entering the upper half of the case.

[albert]

Interesting. I'd not thought about that option. Hmm...I might have to do some more sketches. Thanks.