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Fan Flow Direction

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February 27, 2012 1:11:20 PM

Hello,

I've got an older full tower case with a fan in the bottom front. The fan is connected to a power plug. With my new mb I replaced the front fan so I could connected it to the fan plug on it so I can have it monitored in the system. The old fan wasn't a high output and it sucked air in at the bottom and the power supply pushed it out at the top. The front of the case even has a large slot at the bottom for the air to come in.

The new fan I got pushes air out the front of the case instead of sucking it in. How can I change the direction of the flow or shouldn't I as the new fan really pushes the air compared to the old one. I'm wondering if the extra air flow that would come into the case wouldn't go out fast enough thru the power supply and cause a higher pressure inside the case.

Thanks

More about : fan flow direction

a c 139 ) Power supply
February 27, 2012 1:20:09 PM

gb777 said:
The new fan I got pushes air out the front of the case instead of sucking it in. How can I change the direction of the flow
Hello gb777;

You should change the front fan to intake.
Just flip the fan around and you'll have it sucking cool air back into the case.
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February 27, 2012 1:23:47 PM

Thanks but I did that and the other side of the fan is too close to the grate and it sounds like a jet about to take off. The side with the label on it that goes up against the grate is recessed a bit (like the old one) and the other side almost touches it with the spinning fan. I wonder why the new fan flow is opposite the other one?

That diagram is great. Confirms I need the fan to suck in and it's been working correct all these years.
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a c 139 ) Power supply
February 27, 2012 1:24:59 PM

What fan did you buy?
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February 27, 2012 1:28:52 PM

front bottom and side for intake, rear and top for out-take.
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a b ) Power supply
February 27, 2012 1:34:00 PM

Which fan have you bought?
A fan flows in a single direction only. There'll be an arrow mark on the side of the fan showing the direction of its airflow.
From what you have mentioned, your fan is thicker & has a higher rpm than your previous fan, hence its louder.
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February 27, 2012 1:47:18 PM

Masscool 80mm at Compusa. It has 3 wires as opposed to the 2 that plug into the power plug. I'll have to check for the arrow.
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a b ) Power supply
February 27, 2012 1:58:52 PM

A 2500rpm fan will be loud.
Either bear the sound or swap it with a silent one. :) 
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a c 139 ) Power supply
February 27, 2012 2:02:49 PM

Will your case only accept 80mm fans?
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February 27, 2012 5:12:51 PM

The case will only accept a 80mm fan.

The fan is only loud when it's sucking air in not when it's pushing it out.

The noise is from the air not the fan.
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February 27, 2012 5:25:28 PM

gb777 said:
The case will only accept a 80mm fan.

The fan is only loud when it's sucking air in not when it's pushing it out.

The noise is from the air not the fan.


Air doesn't make noise by itself... air makes noise moving over a surface, like a fan. There may be some rubbing of the fan against the chassis.
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February 27, 2012 5:42:11 PM

I swapped out the original power plug fan and the mb plug fan to see what makes it loud. When holding it out of the case and running, it's pretty quiet. When mounted with the non-moving face side with label next to the grate, it's also pretty quiet. When I flip it around with the moving fan against the grate, it's got a whine to it like a jet engine. The original fan is a bit louder mounted the same way but not as much. I actually think when it's sucking, the fan pulls out a bit as it's got some vacuum against the grate. When it's pushing air out, the fan is pushed into it's housing more.

Are you guys saying a quiet fan will be much quieter when mounted so it sucks air in? Perhaps a ball bearing fan? I put the original fan back in for now.

Thanks
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February 27, 2012 5:50:14 PM

sometimes the vibration is making the sound or somethings rubbing the spinning fan. I've shimmed the fan with stacked pieces of tape (masking, duct, scotch) at each screw point of the fan. it'll isolate some of the vibration as well as shim the fan from the mounting surface that be be hitting the rotating fan.

airdeano
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February 27, 2012 5:54:33 PM

gb777 said:

Are you guys saying a quiet fan will be much quieter when mounted so it sucks air in?

Thanks


Yes, quiet fans are quieter.

The fan moves the exact same way no matter what. you are just pointing the fan in a different direction to direct the flow. The same pressures are in place no matter what. If the fan is creating a vacuum (it is that is how they work) it is creating the same vacuum no matter what direction you are pointing it in.

I recommend making a fan shroud out of you older/ louder fan to prevent any rubbing that may produce noise. Just snip out the 'fan' part of the crappier fan with a pair of diagonal cutters(dykes) and throw it in the trash. Mount your nicer fan to the 'shroud' and attach to the case.
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February 27, 2012 7:12:53 PM

pacioli said:
I recommend making a fan shroud out of you older/ louder fan to prevent any rubbing that may produce noise. Just snip out the 'fan' part of the crappier fan with a pair of diagonal cutters(dykes) and throw it in the trash. Mount your nicer fan to the 'shroud' and attach to the case.

That is a fantastic idea!! I have a couple saved 80mm fans from junk power supplies. Works like a charm. Quiet as can be and I can monitor it in the CMOS. The jet has landed!!!

Thanks!!
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February 27, 2012 7:27:40 PM

gb777 said:
That is a fantastic idea!! I have a couple saved 80mm fans from junk power supplies. Works like a charm. Quiet as can be and I can monitor it in the CMOS. The jet has landed!!!

Thanks!!


You are welcome!
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