Fan's Audible Vibrations

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Saturn

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I have a small fan that spins at around 9200 rpm. Do fans even do this anymore? My case will shake and you can hear it spin up. Heck, you can hear it all the time. It isn't installed loosely, either. Is this just because of its high rpm? or should that speed be ok?

:cool: <font color=blue> Blowing things up smells aweful... </font color=blue>
 
R

Red_Zealot

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Wow....that's a lot of RPMs. Must make a crapload of noise. Delta 38s (loudest anybody can stand, IMHO) spin at like 7200 RPM.

"If you teach a child to read, then he or her will be able to pass a literacy test" - George W.
 
R

Red_Zealot

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Wow..I think I'll buy one with the Alpha 8045...Can you imagine the performance??? My temps will decrease by like 5C!!!!

//At some point, the noise insanity must end...

"If you teach a child to read, then he or her will be able to pass a literacy test" - George W.
 
flamethrower205

flamethrower205

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Is it possible to OC a fan- imagine, 16K RPM delta that's water cooled. Hehe. Oh man that would be loud. How much do deltas cost? EMay install one just FOR the noise.

U got a problem?! Then dial 1800-328-7448!
 
flamethrower205

flamethrower205

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Ok, where can I get an 8K? I LOVE THE SOUND OF FANS (ok, I belong in a mental asylum). My friends and I have this thing going where whoever has teh highest rotation fan has teh bets computer, regrdless of parts (yeah, it's stupid but fun). And w/ an 8K, I will be king:)

U got a problem?! Then dial 1800-328-7448!
 
flamethrower205

flamethrower205

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Just thought of teh best combo: Delta 8K to cool PSU, an 8K for the GPU, an 8K for the mobo, 3 8K's for teh case, and 2 8K's for teh CPU! Ha, imagine that noise!

U got a problem?! Then dial 1800-328-7448!
 
lhgpoobaa

lhgpoobaa

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yeah... you can get some wikked 40mm or 50mm fans that spin at amazing bad speeds....
yet they still only move relatively small amounts of air

Religious wars are 2 groups of people fighting over who has the best imaginary friend.
 
G

Guest

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Hi Folks,

Just some insight regarding the fan noise produced at 9200 RPM.

As any fan spins, the blade moving through the air creates vortices of air trailing behind the edges of the blades. These vortices lead to pressure waves that our brains interpret as sound.

If a fan blade is moving faster through the air, it can create a more turbulent flow, and thus a more powerful pressure wave (a louder noise). Bear in mind that high RPMs do not necessarily translate into higher velocity for the blade edges (the outside edges of the blades produce the vortices). For example, high RPM on a small fan may still be very quiet, as the the blade edge velocity may be low. Lower RPM on a large fan may be much louder. Of course, most CPU fans are approximately the same size, so higher RPM usually does mean more noise.

How, then, can we make a quiet fan that still moves more air? Well, when the application is to keep a CPU cool, sometimes just putting the same fan in a better location will move more air. This, of course, is not a fan design issue, but rather a case design issue.

What, then, can we do to fan blade design to accomplish a more laminar flow? This is the question that people much smarter than me have invested years in studying, and if you can come up with an answer, then early retirement is all you.

<A HREF="http://bible.gospelcom.net/cgi-bin/bible?passage=PS+17:7-9" target="_new"> PS 17 </A>
 
K

knowan

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The noise and vibration may be caused by an unbalanced fan. If one of the blades of the fan is damaged/imperfect, it will unbalance the entire fan assembly. If this is the case then as the fan spins around, it will also be shaking back and forth/side to side at 9200 times a second, causing the vibration.

Suggestions: to tame the noise a bit, clean the fan (it's probably pretty dusty) and mount it with rubber gromits between the screws and the case. The rubber gromits will deaden the vibration.

This day and age noisey fans are normal, but a fan which causes your case to vibrate is not. The cause of this is most likely an unbalanced fan, but repairing the fan will cost about as much as replacing it with a new one.

Knowan likes you. Knowan is your friend. Knowan thinks you're great.
 
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SerArthurDayne

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Hrmm.... if the 7200 RPM Delta is a "fingerchopper fan", these 9200 RPM fans must be "fingerfrappe fans"

/me advises Flame to invest in many fan grilles

"Laziness is a talent to be cultivated like any other" - Walter Slovotsky
 
S

Saturn

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The 9200 rpm fan I asked about in the first post is about 1.5 to 2 inches in diameter. It is pretty small compared to most other fans I encounter. There is no visible damage, such as chipping on the fan blades. Ever since day one it has created the same amount of noise and vibrated the case. Most of the noise comes from the vibrations when I mount the fan on my heatsink. When I hold it in my hands it seems very quiet, but I can feel it vibrate. Could it be that ball bearings can't handle such high speeds without vibrating?

:cool: <font color=blue> Blowing things up smells aweful... </font color=blue>
 
F

FatBurger

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My suspicion is that it is not perfectly weighted (in other words, off balance), so it wobbles a bit when it spins. At lesser speeds it wouldn't be as noticeable, but since it is spinning so fast, it's easily felt.

<font color=green>I post so you don't have to!
9/11 - RIP</font color=green>
 
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