Korean Job Discussion Forums

JustJohn · Joined: 18 Oct 2007 Location: Your computer screen

So apparently there are two schools of thought on this, well three I guess.

1. You should have more fans blowing IN because this will create a high pressure zone in the case, thereby keeping more dust out.

2. You should have more fans blowing OUT because this will create a low pressure zone, and PV=nRT (ie: pressure goes down, temp goes down)

3. Keep it equal because ... ? (I think I heard someone say you get the most airflow that way...)

So, after evaluating each of these statements, I'm not sure if I'm convinced of the logic in any of the arguments (1. more sucking = more dust doesn't it? 2. Equation is for a closed system. 3. Not sure about) Does anyone have a convincing reason for doing it one way or another?

ttompatz · Joined: 05 Sep 2005 Location: Kwangju, South Korea

mnhnhyouh · Joined: 21 Nov 2006 Location: The Middle Kingdom

If pressure had a difference I would think high pressure would be better, and this is why.

Each piece of air in a higher pressure system will have more molecules. More molecules in that air means more molecules hitting the heat source in a set time, which means more heat transfer.

However I think the overriding concern is as ^ said, moving the most air through the case.

I would guess that it would be better having the outgoing fans at the top, so their hot air rises away from the intake fan on the bottom.

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JustJohn · Joined: 18 Oct 2007 Location: Your computer screen

Not all cases are full of holes. A (very) few of them are near perfect seals aside from the fans.

I'm pretty sure high pressure for "more molucules -> more heat transfer" doesn't work. Like I said, your ambient temp goes up if you increase the pressure, so you'd get less differential and thus LESS heat transfer.

As for the other comment, of course increased airflow is better, but will changing the fan balance make an appreciable difference? I'm not sure.

Ut videam · Joined: 07 Dec 2007 Location: Pocheon-si, Gyeonggi-do

JustJohn · Joined: 18 Oct 2007 Location: Your computer screen

I wouldn't say it doesn't come into play. The air pressure in your case is likely to be slightly different than outside it. In fact, I imagine you should be able to create a fairly significant low or high pressure zone if you're using small fans.

eamo · Joined: 08 Mar 2003 Location: Shepherd's Bush, 1964.

IMO, it's better to have a stronger fan at the back exhausting the hot air. Of course, a strong fan at the front would be nice too......but only if it's quiet.

But I would generally focus on the rear fan being strong.

I don't think a PC's internal air pressure is really going to build up much due to the vents. Unless you seal the vents then air pressure isn't really going to come into play.

It's all about airflow from front to rear.