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Positive or Negative Pressure

3dGameMan...hmmm...stupid name, but he explained it pretty clearly.

One thing to remember...you don't actually reduce the amount of dust in a positive pressure setup, you just focus it where the intakes are.

There are some situations where having more exhaust works better, but I've found very few of those in my personal experience.
 
Originally posted by: WoodButcher
Neither is better in all circumstances. Your case, hardware and where the case is located are the key.
Click to expand...

Yup, every case has its own peculiarities. I tend to get better results with more intake than exhaust. I actually had the standard rear exhaust fan fail on my PC and my temps (before I discovered it) actually went down. I had a total of three intake and only one exhaust (top) before I discovered the failure. Almost didn't replace it, but something about the empty slot bugged me. :laugh:
 
I agree with yh125d that balance is most important. Also air FLOW is most important i.e. front to back, or front to top etc. There needs to be a method to the madness with fans...you cant just have random fans blowing stuff around. You need to create a current.
 
Originally posted by: blackangst1
I agree with yh125d that balance is most important. Also air FLOW is most important i.e. front to back, or front to top etc. There needs to be a method to the madness with fans...you cant just have random fans blowing stuff around. You need to create a current.
Click to expand...

Just my two-cents worth, and prior posts I'd made may have dispelled myths about pressurization. Pressurizing the case (Intake CFM > Exhaust CFM) is to be preferred with certain caveats:

IF: There are no pockets of stale air, or airflow and movement is sufficient throughout the case, or there is always some airflow over any and all components that generate heat.

IF: Some effort is made to channel airflow to minimize a mixing of general case-interior air with air that has been warmed by components. CONVERSE: air that has passed over components (warmer than intake air) should be exhausted immediately.

IF: Intake air is forced through the fins of a CPU heatpipe cooler; THEN: higher pressure means denser air and slightly better heat-capacity of air and better cooling.

All of this in context of "balance:" The combination of intake and exhaust fans should lead to mild pressurization of case-interior air; a strategic "channeling" of air through "ducting," case-design or other means may offer opportunities to reduce the total number of fans overall; the number or fans, size of fans, CFM of fans and RPM of component fans offers a trade-off with noise in dBA. [Thus, three 120mm intake fans with RPM of 1,500 RPM-each, and CFM of 90, will produce less noise than two 120mm intake fans with RPM>2,000 and CFM of 90.]
 
Ten years ago I bought a computer from a "Mom & Pop" store that accidently had two fans exhausting, one in front and one in rear.

Air came in thru holes in the side of the case. That thing was a real vacuum cleaner. A few months later I looked inside and there was a "blanket" of dust an inch thick that I "rolled" up to remove.

After turning the front fan around the thing stayed much cleaner.

Ahem ... no comments on my wifes cleaning habits or lack thereof 😀
 
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