Is 21.2dBA loud for a fan?

Guitarman0 · 7 Jun 2010 at 22:15

As the title says, is 21.2dBA loud for a case fan?

Thanks

Raikiri · 7 Jun 2010 at 22:38

Not if it's an accurate reading, which it won't be

roadie · 8 Jun 2010 at 13:21

I find RPM to be a more accurate figure for the amount of noise you can expect from a fan than the manufacturer's dBA figures, which seem to be essentially made up for the most part. Under 1000RPM normally equates to a quiet fan in my subjective opinion.

ricky · 8 Jun 2010 at 13:36

Which fan is it?

Guest2 · 8 Jun 2010 at 13:57

roadie said:
Under 1000RPM normally equates to a quiet fan in my subjective opinion.

2 fans at 1000RPM is less noisy that a 1900RPM fan

How come 2 1000RPM fans move a lot less air than 1 1900RPM fan?

shadowscotland · 8 Jun 2010 at 21:36

fluid dynamics is your answer Guest2.
and a high rmp fan also usually have much higher static presure.
Which is why a good case fan is not the same as a good HS fan

dBA should always have a distance attached to it (but there never is)
so the fan companies don't lie - they just don't tell you the dBA was measured +4m away in a room filled with soft furnishings

Also each additional fan add 3dB to the base noise level of the first.
2 fans + 3dB = twice as loud (but not necessarily twice as noisy)
3 fans + 6dB = 4x louder (twice, twice)
4 fans + 9db = 8x louder (twice, twice, twice) etc.

And just incase that wasn't enough the sound signature of every fan (low rumble of motor with added higher pitch woosh of air) is different too.
two noises may have the same energy (dB) but one 'sounds' louder
this is where dBA comes in, it's a value that's bias to how the human ear hears things.

spcr is the only site i trust when compairing fans as they use a Anechoic Chamber.
But as i said above a 'quiet' low rmp fan is usually best for cases only - noctua, noiseblockers etc are rubish on most HS and thin rads

MouthBoy · 8 Jun 2010 at 22:57

6 of these then would equate too 19db + (6 x 3db) = 37db?

shadowscotland · 9 Jun 2010 at 03:59

that's the theory - and why I use only the one fan

ultrakipper · 9 Jun 2010 at 05:39

Guitarman0 said:
As the title says, is 21.2dBA loud for a case fan?

Thanks

Search the net for the fan you already have then compaire the DB with others to give you an idea of how loud / quiet it will be.

Hotwired · 9 Jun 2010 at 05:45

There's lies, dammed lies and there's fan specs.

Apaches for example, laughable air pressure numbers which managed to make it to many sites across the internet and even have the 26.40mm H2O air pressure claim on the dam box. Throw in low noise claims which no two manufacturers have the same methods for and there's nothing to believe apart from that green/brown is a horrible fan colour scheme.

Guitarman0 · 9 Jun 2010 at 07:53

ricky said:
Which fan is it?

Thanks for the replies, and I bought the fan in the end. It was this one.

(http://www.overclockers.co.uk/showproduct.php?prodid=FG-000-XI&groupid=701&catid=57&subcat=4)

Raikiri · 9 Jun 2010 at 12:48

They're ok, but not 21dB. Probably closer to 30.

xiphrex · 9 Jun 2010 at 15:05

roadie said:
I find RPM to be a more accurate figure for the amount of noise you can expect from a fan than the manufacturer's dBA figures, which seem to be essentially made up for the most part. Under 1000RPM normally equates to a quiet fan in my subjective opinion.

Definitely agree with you, whatever fan I have tried and I have a wide range of fans now, under 1000 RPM seems to be tolerable sound but over that and you can definitely hear it.

Also I should add that it depends on your case as well. If you have a case with minimal holes, no side fan hole, no top fan hole, the case is going to be more sound proof and allow less sound to escape. If I take the side panel off my case the whole thing is immediately noticeably louder.