Diffent speeds on exhaust fans in the same case?

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where?wolf
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Diffent speeds on exhaust fans in the same case?

Post by where?wolf » Thu Mar 15, 2007 5:09 am

I'm just wondering if it's a bad move to have different speeds on the rear and top exhaust fans in a P180 case?

Let's say, you have 2 fans of the same stock speed performance.

And now, you are intending to run the top exhaust at 650rpm and the rear fan at 850rpm.

Would the fan at 850rpm, render the 650 rpm useless? As the the 850 have the higher cfm?

miahallen
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useless? no

Post by miahallen » Thu Mar 15, 2007 7:18 am

It wouldn't render the slower one useless, but it could create weird airflow. It's probably best to try it and see the results for yourself.

Bluefront
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Post by Bluefront » Thu Mar 15, 2007 7:19 am

The slower running fan probably will not be affected enough to measure. Consider the PSU fan.....runs at a different speed than the case fans. As long as air can easily enter the case, you'll be ok.....
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where?wolf
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Post by where?wolf » Thu Mar 15, 2007 7:48 am

O.k.

Thanks guys!

I will try and see what happends?

where?wolf
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Post by where?wolf » Thu Mar 15, 2007 8:55 am

Hi again!

This is interesting.

I lowered the top fan to 650 rpm. And as said, the rear exhaust fan is at 850 rpm (Noctua 1200 rpm fans). And I got 2C lower temp, both idle and load. The case temp also dropped by 2C.

Wonder why?

GuyScharf
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Post by GuyScharf » Thu Mar 15, 2007 8:59 am

where?wolf wrote:I lowered the top fan to 650 rpm. And as said, the rear exhaust fan is at 850 rpm (Noctua 1200 rpm fans). And I got 2C lower temp, both idle and load. The case temp also dropped by 2C.
That behavior begs you to turn the top fan off entirely and see what happens. If that's good, then try blocking the top hole completely.

Let us know. I plan to try such experiments after I get done fiddling with the innards of my P180.

Guy
P180B+3 Scythe S-Flex E, P5W DH Deluxe, Xeon 3070(E6700), Tuniq Tower + S-Flex F + X-23, 4x1Gb G.Skill 800-C4, PowerColor AX5750 fanless, SATA: Intel 80GB SSD, 2 Samsung 1TB, 1 Seagate 750GB, 2 internal mobile racks, Samsung DVDRW, Seasonic S12+ 650w; Dell U2711.

where?wolf
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Post by where?wolf » Thu Mar 15, 2007 9:58 am

Hi!


I did that before with good results. Both removing the top fan and sealing the top hole that is. So try it. It works very well! When I had that config. I just had the rear exhaust fan ducted to the Ninja cpu cooler. No other case fan.

The reason why I have the top fan back on again, is that I have a pretty low speed AMD 3000+.

And when I whas waiting for my 8800GTS videocard. I feldt, I needed more speed out of the cpu. So I overclocked it 400 MHz. And added the top fan, as a support fan, to get rid of the heat from 8800gts.

But as it is now, I have still a silent rig with good temperatures.

The only noise I have, is the low rush of air thru the intakes. And that is what I would call a "harmonic noise", that is'nt bothering me much.

Later on, I will duct the 4 top openings on the 8000gts cooler to a PCI opening in the case. And see if this will help so much, I'm able remove the top fan again and seal the top hole?

miahallen
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another idea

Post by miahallen » Thu Mar 15, 2007 8:52 pm

You could also try replacing the duct from the rear fan to the CPU cooler, then turn the top fan around, so it acts as an intake.

where?wolf
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Post by where?wolf » Fri Mar 16, 2007 2:40 am

Thanks for the tip.

I have a extra, passive intake in the top 3 X 5.25 cd bays , with a 120mm fan filter.

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