Fan speed - cfm - db question

[mrupgrd]

If i have a 4000rpm / 190cfm / 59dBA fan and i ran it at 50% rpm would other things half or isn't it like that?

 

[Anubis]

i woudl assume that THIS is the fanyou are talking about

when you run a fan at lesser voltage like that is not exact but close, BUT that fan will not run at anything other then full speed, because of its HUGE poer rewuirements, hell it takes 3 amps to just start the damn thing

a 92mm Vantec Tornado takes 1 amp and that is a lot

 

[ZUnit]

Nice fan, my current push 75 cfm on 6000 rpm with 55 dB, but its just 80 mm.
I think i'll get one of this if its really pushing 190 cfm and run it at half speed or smth. Actually i am about to build quiet system heh.

I think of course you get less cfm mrupgrd if u run this fan on 2000 rpm, how much less, i dont know maybe half.

 

[Degrador]

If you ran a fan at 50% power, its rpm and cfm should halve, however the sound level (dB) would not halve. It's hard to predict exactly how much it would reduce, but it would be at least 3dB (the equivalent of half the noise level), but probably go lower due to less rattling from lowered speed.

 

[Hyperlite]

wow that is one b!tchin fan.

 

[mrupgrd]

it is that fan i've had my eye on but webby I saw on didnt mention "no rheostat" arrgghh. Was kinda extreme end i was lookin at but with an option to turn down via the hardcano I'll be using.

http://www.overclockers.co.uk/...alogue_YS_Tech_60.html

the 2 at the bottom of that page seem a bit more reasonable..

tho if i get the XP-120 I may just have to try that Delta for the crack

 

[AsiLuc]

That's one crazy fan!
The RPM would go down half +- 10%, but CFM would certainly drop to 40% max. dB won't drop as much as you would like it to, though.
How about just gettin' an Antec fan? They're really silent and push quite some air.

 

[L00PY]

Originally posted by: Degrador
It's hard to predict exactly how much it would reduce, but it would be at least 3dB (the equivalent of half the noise level), but probably go lower due to less rattling from lowered speed.

Actually it's easy to predict based on the fan laws -- dropping RPMs by half reduces noise by around 15 dBA -- a significant amount. Of course this is just a theoretical prediction and reality is often very different.