IwubAMD

normally when thinking about things like this i just do some math and do the answer, but i dont know much about the properties of sound

my question is this, whats louder 1 120mm fan thats 60DB or 2 80mm fans that are 30 DB

everyone says that 120mm are quieter and put out more airflow, so i wanted to get a case with a lot fo those for my next pc, but they are louder

im basically trying to figure if they are quiter because theres only one, or because u can tone down the rpms... or what <_<

my pc has been off probably a total of 3 days in the past 3 years, and dureing those times i was scared of the quiet

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3dmark06 13205 marks

Computers dont do what you want; they do what you tell them to.

Semi custom Danger den split level case
Lapped 120X
Lapped Q6600 G0 to accompany it!

My car: 1 2 BMW 335i coupe TT 440HP 460TQ!
(yea i have an extreme need for speed in every aspect of my life )

aznchowboy650

the 120 60db will push more air flow but for lower noise 2 30 dba should be lower

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busa

The 120 would be louder. 2 x30db does not equal 60db.

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Stinger Slingers V5
insanity reigns
It's better to reign in hell than serve in heaven.
There is more to life than increasing its speed. - Mahatma Gandhi...guess he's not a member of Overclock.net
Kickin avatar by "Crash"....

aznchowboy650

Agreed becuase Dba increases exponentially so a 60dba is more than 2x louder than a 30dba

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IwubAMD

i know i figured that, but then why are people saying 120s are quieter..

__________________
3dmark06 13205 marks

Computers dont do what you want; they do what you tell them to.

Semi custom Danger den split level case
Lapped 120X
Lapped Q6600 G0 to accompany it!

My car: 1 2 BMW 335i coupe TT 440HP 460TQ!
(yea i have an extreme need for speed in every aspect of my life )

busa

They can push the same air at a lower rpm. A 120 w/50cfm at 1000rpm will be much quiter than an 80 at 3000 rpm to push the same 50cfm.

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Stinger Slingers V5
insanity reigns
It's better to reign in hell than serve in heaven.
There is more to life than increasing its speed. - Mahatma Gandhi...guess he's not a member of Overclock.net
Kickin avatar by "Crash"....

--Filip--

Ok there's a number of reasons. The lower RPM for one, produces a lower, hence less noticeable frequency. Also the larger mass of the frame and blades makes them produce lower frequency noises.

So they spin slower and produce lower pitched noises hence making them way quieter than 80mm's.

http://www.overclock.net/showthread.php?t=29166

Interesting read^

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Ex-PC overclocker.
I'm from the AMD64/P4 days...

Now rocking a laptop

fstfrddy

Listen, one of the best things you can do to reduce fan noise is to take a dremel and cut out those da*n swiss cheese fan grates in your case and just use a wire grill. Those things create a lot of noise. Believe me it makes a big difference.

Veto1024

1 120mm fan by far. The dB system is logarithmic and the rule of thumb is something to the effect of 'for every 3dB increase, the power of the sound is doubled'.

Because they don't need to spin as fast to generate a decent amount of air. If you had a 120mm going fast enough to generate 60dB of noise...you're going to be pushing a tremendous amoutn of air. A normal 120mm fan can generate 120+ CFM at only 42 dB or so. A 60mm can hit 50 CFM but would be going fast enough to generate a 50-60dB noise. Hmm... i wonder how much air a 120mm fan going fast enough to create a 60dB sound can move.