Question two silent wings pwm 140 or 120mm intake fans

ConradWebster

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Given that positive pressure equals less dust and only one 120mm rear exhaust fan is possible, is it better to have two 140 or two 120 pwm intake fans? 140's can run slower but would they be excessive even though they have to pull air in through side front vented Fractal Design Define 7 Compact or C case?
 

ConradWebster

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Hadn't really thought about that. The 7 Compact comes with a 140 front and 120 exhaust so would add a 140 pwm to the front. The Fractal C has two 120. As you say, two 120 pwm front and one 120 pwm exhaust might look better - one review suggested this, but the two 140s would be the same as the 7 Compact . 140's more efficient and could lower speed. Still decided .
 
Hadn't really thought about that. The 7 Compact comes with a 140 front and 120 exhaust so would add a 140 pwm to the front. The Fractal C has two 120. As you say, two 120 pwm front and one 120 pwm exhaust might look better - one review suggested this, but the two 140s would be the same as the 7 Compact . 140's more efficient and could lower speed. Still decided .
Always use largest possible, for same airflow they are quietest. Disparity between 140 intake and 120 exhaust is too small to be noticeable in any way. Larger one at intake has some edge because any "extra" air pressure will find a way out somewhere.
 
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ConradWebster

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I would have two x 140mm intake and one x 120mm exhaust. The intake has to work against filter and front panel whereas the exhaust has no restrictions. Also, most seem to believe positive pressure is best, as you say, so air will filter out and there should be no dust build up. With pwm I can slow intake if there is any problem. I seem to have decided what to do.
 

Phaaze88

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So much what CountMike said, but I think it's a bit questionable with 200mm.
140mm can have a more pleasant sound profile too.

The fan that the user can more comfortably run towards 100% rpm is the one that 'wins'.

the exhaust has no restrictions.
Exhaust does have a restriction - the grille and hole pattern causes some blowback.
You can't ignore that unless you take a dremel and cut it out.



Dust is inevitable. Set up a cleaning schedule. Also, the higher off the floor, the better.
Ironically, it's the airflow restrained chassis that introduce a lower dust volume, but they aren't going to be as thermally sound as an open mesh one.
Pick your poison, I guess.
 
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Larger fans are always better, 2x 140mm intakes move the same amount of air as 3x 120mm while being quieter.

Stop caring about positive or negative pressures, dust is an unwinnable battle. Get an anti-static blower and blow out your PC of dust once in a while.
 
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mikewinddale

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As several others have said, use 140mm whenever possible. You'll either get more airflow for the same noise, or less noise for the same airflow.

I notice your case also has a top fan slot. If you can, I suggest you use a rear INTAKE and put some top exhaust in there. You'll get fantastic cooling that way. And if you're using silent fans with PWM from be quiet! or Noctua, you'll barely hear the fans anyway.

Here on Youtube, someone tested temperatures with a variety of different fan configurations, some with positive pressure, some with negative, and some with neutral. He found that negative pressure - where every single fan is exhaust, and not a single fan is intake - gives the best overall temperatures, but of course, it promotes dust. Of all the positive pressure setups, the best temperatures were obtained using REAR INTAKE and top exhaust. I took some screenshots from the video and combined them into one image.

(I say "overall temperatures" because each setup has tradeoffs. For example, #1 has the best CPU temperature but almost the worst GPU and motherboard temperature. Meanwhile, #3 has the best VGA but the worst CPU. Overall, #4 is the best in terms of temperatures, while #2 is second-best. But #2 is positive pressure, so it will reduce dust.)

Of course, this assumes your CPU heatsink either blows towards the top, or towards the motherboard. If your CPU blows to the rear, then having a rear intake will just create turbulence and dead zones.

 
Last edited:

ConradWebster

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Most replies seem to utilise No 3, one points out that the front top exhaust is removing airflow from the front top before it has had any effect. What about ambient? And did they have a quality CPU fan like the Dark Rock 4? I will stick with two 140mm pwm intakes and one 120mm exhaust probably over three 120 mm intakes and one exhaust.
 

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