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Can you stack two cpu fans on each other?

I

impronto

Limp Gawd
Joined
Jul 1, 2004
Messages
137
I have an slk-947u on a 2600+ mobile. I have 2 92mm fans. can i somehow stack the two to increase cfm. Is this bad? Lemme know. thanks
 
Plug in your second fan and hold it over the first. It will get loud and won't perform much better. When the blades are spinning the same way you just create a lot of air turbulence.
 
stick with one fan, even if you were to get a benefit in cfm from two (which you wont) it would not give you any real tangible cooling benefits.
 
Yeah, it's not going to really create anymore CFM, becuase if one fan is say both fans are moving 40cfm, then the fan your blowing air into will only move 40 cfm even if you increase the amount of cfm of the 2nd fan.
 
you can do it, the biggest problem i would see is the added weight to your cpu
the best way to do it is to have a counter-rotating fan with airflow in the same direction
 
How's this for some screwy reasoning?

Stacked fans won't work.

It's not like a 100-mph baseball pitcher throwing a ball from a car doing 100mph (which, if air resistance isn't taken into account, would make the ball travel 200mph).

Rather, it is more like a situation where you have two pitchers that can throw a ball at 100mph. One pitcher can throw it to the other who immediately then pitches the ball as well. . . but it's still only going to be going 100mph when it leaves the 2nd pitchers arm because he gains no benefit from how fast the ball was going when it reached him.

Indeed, I'd say that that analogy is lacking in that it doesn't take into account the airflow disruption and turbulence that the second fan will probably have to deal with due to the first one's mucking things up.

Each fan is designed to move stagnant air up to a given speed. But, those fan blades are only moving so fast.
 
The air will only move as fast as each fan, to 40cfm fans, won't flow 80cfm, only 40cfm. Like electricity through a resistor, no matter how much electricity you put to that resistor, only a certain amount will come out the other side. The only thing you'd gain by having 2 fans like that would be redundancy, and they do this in server machines, at least a couple of the microns we've bought.
 
pstang said:
the best way to do it is to have a counter-rotating fan with airflow in the same direction
Click to expand...

This is correct. There are benefits if the fans are rotating opposite directions (with air moving the same way). If the fans are moving the same direction, though, there's just a lot of added turbulence.
 
RawsonDR said:
This is correct. There are benefits if the fans are rotating opposite directions (with air moving the same way). If the fans are moving the same direction, though, there's just a lot of added turbulence.
Click to expand...

This would be more efficient because both fans would be assisting eachother in moving the air, this way there would be less of a load on the motors.
 
Fans in parallel: increased CFM
Fans in series: increased airpressure

Stacked fans will be noisier than single or parallel fans, unless you reduce the turbulence of the airflow leaving each fan.
 
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