Positive pressure or negative?

[blueonblack]

I've read both sides of this issue, wanted to get some opinions here. First of all, cooling is NOT an issue. I'm doing a scratchbuild, with plenty of airflow, and either way will cool the system just fine. However, I've heard different things about dust buildup. This is an all-acrylic build, and dust will be my enemy. Which will present less dust problem, a positive-pressure air cooling system or a negative-pressure air cooling system? Or is there any difference at all?
________
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[crenn]

Either way, dust is going to get into your system. I personally use negative-pressure.

[xmastree]

With positive pressure you know where the air is getting in so you can filter it.
If it's in a dusty environment, negative pressure will suck dust in every gap it can.

[J-Roc]

fan filters are your best bet. And i think the best system is a neutral pressure system where there are just as many fans sucking in as there are blowing out. That way, you know where the air is coming and going from.

[crenn]

Problem with fan filters is they do clog... and when they clog..... less airflow which means if you have a neutral system... it's now a negative pressure system.

[xmastree]

That's why it should be positive...

[Airbozo]

Looking at _most_ professional servers, they all use positive pressure flow. There are usually more fans sucking air in, than there are evacuating it. On the sgi Origin 3000 and altix systems (super computers), there are no fans expelling air, only fans sucking air in.

On the supermicro builds I am doing, there are 4 fans just behind the drive bays pulling air in and 2 smaller ones just above the cpu/memory area sucking air out and 3 very small fans sucking air through the PSU's (3 of them for redundancy).

http://supermicro.com/products/chassis/3U/833/SC833T-R760.cfm

Notice the air baffle that covers the CPU's and memory and directs the air accordingly.

In my experience most large manufacturers use positive pressure.

[J-Roc]

I guess we all kinda missed the point. The only way to minimize dust inside the case is to use fan filers.

If you have an air purifier or hepa filtration unit, you can put it neer your case to help clean the air around the case.

[si-skyline]

duck tape up every crack other then the intake and outtake, slap on some filters. should work well :)

[xmastree]

I guess we all kinda missed the point. The only way to minimize dust inside the case is to use fan filers.That's what I said


duck tape up every crack other then the intake and outtake, slap on some filters. should work well :)
No need to tape up the cracks if there's positive pressure as air will always come out of the cracks. It's a common technique for equipment used in a dirty environment. I used to work with a piece of test equipment which had a connection for a nitrogen bottle. It didn't have any cooling fans, but this connection was just to pressurise the case to stop crap entering.

[si-skyline]

yeah i know. It seemed a good solution in my head a the time.