Controlling airflow

What are the guidelines to folllow for having a well cooled case? What types of fans should I be looking to put in what positions? Do some cases (ignoring what fans they come with) have better airflow than others? I've heard that some cases are actually designed to use air pressure to direct air appropriately, specifically HP server cases, is there truth to this? I have no idea where to suck, blow, and vent; please advise

Server Cases have always been superior in airflow design because they have to be. Being that thin requires a smaller heatsink that needs to be cooled right ASAP, and the small size lets the air really get through. Also, noise usually isn't a factor when it comes to server racks, and have very powerful fans behind them. Tower cases have the disadvantage of being larger than rack servers and much wider. Personally, for optimum airflow and cooling, I would reccomend searching for a desktop case. They're pretty rare these days, however moving air over them is much more efficient than a large tower.

As for better cases, the topic hasn't been explored in the way that heatsink ratings have, probably because it would require more sophisticated testing equipment, and the results probably wouldn't differ much from case to case. If the case, however, did have a huge gaping hole in the side of it, that would effect the airflow within the case. You don't see many passive vents on enthusiast machines/cases, because it would hinder a precisely controlled airflow environment. The Antec Sonata is probably the worst case (I can think of) if you want to really control your airflow and every last bit of it.

Generally speaking, Lian-Li cases do well containing airflows. Also, a 2 intake (in front) and 2 exhaust (in back) setup is the most common and effective. People prefer a quieter fan for this task, because multiple fans are running and their combined CFM is usually good enough, brands like Panaflo and NMB usually make those kinds of fans.

Whatever you do with the setup, you'll want to either have a balanced amount of airflow (by making sure your fans are the same or very close in specs and quantity within your case) or a what we refer to as positive airflow, that is more air coming in than is getting sucked out (i.e.: 3 intake fans, 2 exhaust)

*Deep Breath*

Here is a link to a certain page of an EXCELLENT heat transfer guide. This page relates specifically to case cooling, but the entire article is definetly worth a read if you want to flip back to the first page and read through the whole thing.

Take a looksy:
http://www.amdmb.com/article-display.php?ArticleID=105&PageID=8

Between those 2 posts and the amdmb link, that entirely answers my question. One thing I forgot to ask though: When taking air in, should some kind of filterting be done to get rid of dust and other particles?

Using a filter on the intake sure can't hurt, and one way or the other you're going to be cleaning dust off of one or more objects so it might as well be a filter.

Just so that a dissenting opinion can be heard....I have had more success with increasing exhaust (negative ventilation) than positive in almost every case I have worked with.
Only 1 or 2 exceptions.

When you say to have more exhaust than intake, you still do have some intake, right?

It seems to make more theoretical sense to have equal amounts of intake and exhaust. I would think that if you had more intake, the air would become too hot; and if you had too much exhaust, there wouldn't be enough air to move around. Then again, I dont know how it actually works in practice.

Yeah, I think he still has 2 intakes, probably 3 or more exhausts. I would imagine it would work well, however when I reccomended the positive airflow, this keeps extra dust from accumulating. I used to have pretty negative airflow in my case, and I could feel air being sucked in from the 5 1/2" bays and just about every crack there was in my case. This resulted it a lot of dust and particles getting in the computer, even more than an unfiltered fan intake would produce in my experiences.