Why do some people complain about 120mm fans?

[Kaspian]

I have 3 120mm fans in my case and the only thing that you can hear is the vga fan. Which m replacing soon.

 

[HardWarrior]

Originally posted by: milleron

Originally posted by: suszterpatt
Actually, twice the pressure is almost exactly a 3dB difference.

I'm confused. What's a 10 db difference?

Not much, if you aren't a noise Nazi. 😉

 

[suszterpatt]

Originally posted by: milleron

Originally posted by: suszterpatt
Actually, twice the pressure is almost exactly a 3dB difference.

I'm confused. What's a 10 db difference?

Nothing special that I know of.

From Wikipedia

A level difference of ±3 dB is roughly double/half power (equal to a ratio of 1.995). That is why it is commonly used as a marking on sound equipment and the like.

[...]

The conversion for decibels is often simplified to: "+3 dB means two times the power and 1.414 times the voltage", and "+6 dB means four times the power and two times the voltage ".

While this is accurate for many situations, it is not exact. As stated above, decibels are defined so that +10 dB means "ten times the power". From this, we calculate that +3 dB actually multiplies the power by 103/10. This is a power ratio of 1.9953 or about 0.25% different from the "times 2" power ratio that is sometimes assumed. A level difference of +6 dB is 3.9811, about 0.5% different from 4.

But in case you want to check for yourself, the formula to get the pressure difference is:

I(db) = 10*log[I/I(0)]

Where I(0) is 2E-5 Pascal, the hearing threshold of the human ear. Take a value of 20dB for example, calculate I, double it and convert it back to dB's. You'll see that it's almost exactly 23dB.

 

[AndyD2k]

I have 4 120mm fans in my pc...

Nexus on the cpu heatsink
two cooler master blue uv fans in the back
1 antec tricool fan in the front set to the medium

The only thing I can make out is the fan on my video card (evga 6800gt). Makes it pointless that I spent all that time researching on what fans to buy for my new pc that were ultra quiet. i may switch out the nexus for a panaflo to improve cpu temps as the added noise can't be that much worse compared to the vid card.

 

[dds14u]

Me a fan n00b. (is that an oxymoron or what)

Are exhaust fans usually 120mm?

 

[suszterpatt]

Originally posted by: dds14u
Me a fan n00b. (is that an oxymoron or what)

Are exhaust fans usually 120mm?

Depends entirely on the case. Newer cases tend to have 120mm slots everywhere, but some older models may only have 80 or 90mm exhausts. Depending on the amount of "unused" space, your thirst for adventure and the availability of the proper tools though, you can turn those into 120mm slots too. 😉

 

[milleron]

Originally posted by: HardWarrior

Originally posted by: milleron

Originally posted by: suszterpatt
Actually, twice the pressure is almost exactly a 3dB difference.

I'm confused. What's a 10 db difference?

Not much, if you aren't a noise Nazi. 😉

Cute. Thanks a lot. I meant to ask what is the multiple of a 10-db differential in sound level.