TG_JBRanger

Alright, I'm gonna preface this with I am no engineer. I have worked amongst them in several HVAC related jobs but that's where my expertise ends. With that said, on with my discussion.

How many fans do you think it takes to cool a pc? 1, 2, or 32,000? Well, with a properly designed case and airflow structure I'd venture to say 1, 2 max should be sufficient. I've looked at several cases and even done some "web" research in this matter. It seems adding tons of fans is actually not good and can even degrade cooling by way of them interfering with each others airflow.

With a larger amount of air coming in you get positive pressure which isn't quite as good as negative for cooling but keeps more dust out. With negative pressure (more air going out) you get better cooling but a haven for dust.

What about placement? Front, rear, side, top? ALL? It actually seems that one rear 120 mm fan is about the best of all solutions for cooling, noise, etc...

So, what say you? I know there are far more educated folks here than myself to enlighten us all and even disprove some of my thoughts.

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Acid

I don't know much about fans either, but I can say that where you place them is key.

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Overlag

i just try and follow TWO rules

1: In at the bottom/front
2: out at the top/back

i try and even out my pressures really, but saying that almost all my cases are negative pressures, so full of dust and cat hairs!

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From Adam Webb

Spyder

One intake, One exhaust, and two circ fans (read: GPU/CPU HSF's) is usually all you will ever need. If your intake and exhaust fans have the same CFM, then your PSU's exhaust fan will generate a slight negative case pressure (more air out than in), which is what most people think is good for air cooling. It is, however, bad for gathering crap inside the case, which is why I use a cleanable filter on my intake. The real key is to keep your core components clear of cluttered wires and such. Wherever possible secure loose wires out of the way. I have my surplus power cables stuck to the top of my case, for example.

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TychoCelchuuu

There's no set number of fans that you need. It depends upon your case, the speed and size of your fans, their placement, and the components you have and how hot they run. I myself use 2 fans, plus my CPU and my PSU which both have fans, while my friend has 4 fans plus one each for his CPU, GPU, and PSU. There is also wiggle room; sometimes you could easily use less fans than you have, but you want to keep your computer cool while it is overclocked or your computer is quieter if you run some fans slowly rather than one fan quickly.

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|TG-Irr|TychoCelchuuu

Scooper

I've got an ASUS Vento 3600 case.
2x80mm intakes (comes with one), 1x120mm exhaust, 1xpassive vent.
Very efficient. I love it.
Google if you wanna chaeck it out.

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Chuck Norris can believe it's not butter

Trooper

i say skip the fans and use cooking oil like they did at tomshardware.com....was cool

KillerTarget

The number of fans depends on many different factors. Some of these include size of the case, if you are overclocking or not (CPU, GPU, anything else you can possibly and would overclock), how many hard drives you have in the case, and how much heat your components produce just by being on.

For a mid tower case like a large portion of the people who own computers have a single 120mm fan in the rear is fine for people who just work on the machine and do nothing else, but if you game or have a lot of components in the case adding another 120mm fan or two would be wise.

For a full tower like my Xaser III from thermaltake the 7 80mm fans that came with the case are perfect for it, I would prefer 120mm fans but they just don't fit, they have air come from front to back and also up and in from the side. While the stock fans are fine for my case currently, I am looking to upgrade them because they don't push enough air through the case for what I am running in my machine. Last year for a friends birthday a group of us joined up and got him a new case because his old case got dropped, the case we got him was a nice Lian-Li full tower aluminum one that came with 2 or 4 fans with room for quite a few more. I know he put more in because he runs a lot of hard drives in his case and they produce a lot of heat, and he also has a lot of other components in the case and with the fans that came with the new case they weren't pushing enough air through it.

Summary:
-Large cases need more fans for more airflow
-Smaller cases should do just fine with the fans that come with the machine unless you have a lot of components in the case

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-BB|KillerTarget

B. Clawhammer

I seem to remember a reading a thread about this on the forums about how a fan blowing air through the top is actually more efficient than having a number of fans in general. I'll see if I can find it in here, but it was at least a month ago I think.

At any rate, I'm using a significant amount of fans, mostly to compliment the lights that originally came w/my case. But I figure more airflow is better than none. I have 4 intakes, a side out, and 2 back outs. A ridiculous number of fans I suppose, but I've never seen my temps for anything go above 40+C and I clean my innards out regularly (about once every 2 wks.) I'd say regular maintenance would be the key to dust build up regardless of how many fans you're using to cool.

PS I don't oveclock and I'm running 2x7800gt in SLI

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Scooper

All you need is adequate flow with a little bit of negative pressure.
Heat rises so a topside "blowhole" fan is good stuff.
It's all about getting the heat out without making the fans work. They need to running, but not under load.
A tad of neg pressure will be cooler by drawing ambient air in through all the cracks and seams in addition to the intake fans capacity. The seam leakage will also ease the load on the intake fans... just a little negative, not much.

Hot stuff like the CPU and GPU(s) need to move the heat away from the units via heatsinks and fans, then that air has to be evacuated efficiently.
Simple as that.

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Chuck Norris can believe it's not butter

Addict

Pretty charts and graphs with a real test of one system with multiple fan configs:

http://www.short-media.com/review.php?r=230

B. Clawhammer

I stand corrected. That article is the one that I read awhile ago. Thanks addict!

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TG_Bubba

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Acid

Oh ya, check out mine.....

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Dick Blonov

Fancy .

You can't go wrong with Antec; they are well made.

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