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  1. #1
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    Lightbulb

    Many people that are concerned about the performance of fans verses noise over look a very key element. I looked over numerous posts and have discovered people are simply using to many fans in their case. Quanity is simply not always better. One should try not to stick so many fans in their case. One should simply make each fan for a particular location as big as the space will allow. For example. I see many people mount two 80 mm fans down low on the side of there case. Which for this application a single 120mm fan would be better suited. Here is some stats. I have used the popular Panaflo H1a for the control.

    Airflow (CFM)
    2 80mm Panoflow (39.6CFM X 2 ) = 79.2 CFM
    1 120mm Panoflow = 108CFM

    Noise (DB)
    2 80mm Panoflow (35DB X 2) = 70 DB
    1 120mm Panoflow = 41.5DB

    Power Consumption (WATTS)
    2 80mm Panoflow (2.1 X 2) = 4.2 WATTS
    1 120mm Panoflow = 5.2 WATTS

    Price (Based on CaseEct)
    2 80mm Panoflow = ($9.99 X 2)=$19.98
    1 120mm Panoflow = $16.99

    Conclusion
    Well the numbers pretty much speak for themselves. If you can sacrafice a little power you will increase airflow, cut down on noise, and save a little money. This is just something to consider when modding your case.



    [Edited by Heckler on 01-28-2001 at 06:36 PM]

  2. #2
    Joined
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    Oh.........quit being a heckler! Your right, but most of the cases out there will simply not allow you to mount a 120mm in them. Hence we mere mortals have to resort to 92's or several 80's. I have found a case, the Palo Alto PA-810 that will allow a 120 mounted above the cpu, and a 92 as an intake. The Yeong Yang cases also allow big fans.

  3. #3
    Joined
    Jun 2000
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    2,203
    I have to agree, but after all it is application specific like Tek says. My thoughts are use common sense, look at the lay out of your case and adjust. In my case, and in my case, the first thing that I needed to do was stop the restriction of air flow into the front of the case. Exhuast has never been a problem as InWin provided two fan mounts on the back of the case, however the intake fan was restricted by the bezel and the metal infrastructure of the case itself. The best away around it was a blowhole straight through the front of the case, then block off the pre-drilled air intakes on the front and side of the case forcing the air to be sucked in from the blowhole. Now it would probably take someone with the ability to do a psycometric(sp) chart based on ambient air temp. and air flow to determine exactly how to "tune" the internal fans (processor and vid. fan) and intake and exhaust fans for optimal cooling and air flow. I'm sure some research has been done on this, but I have yet to see a real white paper done on it, I'd guess that it's done by case manufactures to some degree based on a nominal reference. Sorry for the ramble, just been thinking about this a lot lately.

  4. #4
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    Well, also depends on where you get the fans. For me, all the fans were free. Friend had sold me his addtronics case, and gave me his 2 120mm 3dfx cool fans, i just have all the fans in there cuz I was bored, just wanted to see how many I could really fit in there. 1 120mm in front, 1 120mm in top exhaust. 2 92mm in side, 1 92mm on one side of dvd and cdrw, 1 80mm on other side of dvd and cdrw, 1 92mm on back of psu blowing out, 1 stock 80mm on psu, 2 60mm on hd's, 1 60mm on cpu, 1 60mm on back of mobo tray, 2 60mm on vid card, 1 20mm on via chipset. Have to see it and hear it to believe it. Systems stays ambient at all times.

  5. #5
    Joined
    May 2000
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    1,646
    ummm, your addition to the loudness would be incorrect.
    2x35dB does not equal 75dB, let me explain:
    10dB - very quiet, almost too queit.
    20dB - whispering very queitly
    etcetera.
    10dB is 10x queiter than 20dB, so 50dB is 1000x louder than 20dB.
    but it doesnt seem like that. why? sound is a strnge thing and quite complex.
    two 35dB sources would equal 42dB, roughly. i cant remember the formula bacause its halftime currently.

  6. #6
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    Well, to clear this up a little more. For every wavelength of equal amplitude, an addition of the same wavelength would increase total db by 3db. for each additional wavelength add 3db for each wavelength. So to put this in respect, if you have 3 10db fans, you CANNOT add the db of each fan together. You take the first fan which is 10db, then add 3db for each fan. Therefore the the theoretical decibles should be 16. As for your 35db fans. It would be a total of 38db. ciao...

  7. #7
    Joined
    Jan 2001
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    87

    Talking lol

    lol halftime!

    -CollegeGuy-

  8. #8
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    Question

    Spud, Can you explain a little more clearly. I'm having a hard time finding the logic in that. If a certain object has a certain amount of sound and you add another identical object, wouldn't there be twice as much "noise" as you had before?

  9. #9
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    That is where the 3db comes from. When you add 3db to something, it makes it sound twice as loud. If you were to combine 2 100db fans together, there is no way in hell they would be 200db. It would actually be 103db, so 3db is actually 2x in audible sound.

    Damn, messed up, it is actually 10db for audio db's. It is in electric circuits that is 3db for doubling of signal.
    this should help.
    http://www.cal.shaw.wave.ca/~rboudrea/sound4.html

    [Edited by heise3 on 01-28-2001 at 09:22 PM]

  10. #10
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    Lightbulb

    Ah, I see, So my db calculation is incorrect but there is still twice as much noise. Correct? I have also found another interesting article titled "Two fans, twice the air flow?" Read here: http://www.industrialtechnology.co.u...apr/papst.html

  11. #11
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    Well, if we are only talking about the 2 35db fans, then the output would be 38-45db. That is still very quite. But if you add the 120mm into it, then the minimum db will be that of the 120mm, and added each fan onto that. So your total, (from the top of my head) should be around 48-52db I believe. It will be max of 52, and not a higher number because the louder fan will deadend some of the noise from the smaller fans. I have the formula for all this somewhere. Maybe someday if I find it again I will post it for ya. ciao.

  12. #12
    ddanj is offline the so, so screwed fella
    Joined
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    I just took my Physics SAT 2 exam and your all wrong. if you multiply 32db x2 that would be 30109238481 db's.
    I think thats it.

    -ddanj

    p.s. I don't think I did too well on that test.

  13. #13
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    I think your on to something ddanj, I don't know what yet, but you are definitely on to something......

  14. #14
    Joined
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    Baton Rouge,LA USA
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    2,278

    Talking

    Well 1 300w Antec PSU fan + 2 Sunon 80mm HO fans + Vos-32 w/2 Y.S. Tech 60mm fans = LOUD. To make matters worse I just ordered 2 Black Label 60mm Delta fans for the VOS. Guess that will = Very LOUD

  15. #15
    Joined
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    Location
    Birmingham, AL
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    I have figured out a way to silence a loud case. (mine in particular has 1 80mm antec blowing in in the bottom, 1 80mm antec blowing out the top, 1 60mm blowing out behind the cpu, 1 120mm sunon blowing in from the side to the cpu and video card, plus golden orb (core crusher) and psu fan) Your case will be completely quiet if you put the case on the floor next to the desk and put a box fan about head level next to the desk.
    Here's a link to some pictures of my monster.
    http://www.angelfire.com/geek/thegee...geekstuff.html
    HiFi

    The Crunchers:
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