Has anyone tried stacking two delta fans on one heatsink?

[Sid]

I was wondering if anyone here has tried stacking two 38cfm 60mm delta fans on a single heatsink. Would it create more airflow and cooling or just more noise?

 

[proze]

someone, somewhere (over the rainbow??) did an article on fan-stacking.. the conclusion was that it helped slightlty and created a whole lot more noise. you can try it, though, and see for yourself. it wouldn't be hard to implement at all. if you already have two deltas that is...

 

[batboy]

I read an article where sometimes it actually hurt performance. The main except was if you used one fan that spins clockwise and one that spins counter-clockwise. Otherwise, the two fans are creating too much turbulence and just fight each other.

 

[Kryten]

I gave this a try out of coriosity it gave slightly more air flow but much increased noise

 

[asmodean]

It actually increases the static pressure, which is good. Dunno about the deltas, they do that well enough already. Try stacking 2 60x60x10mm fans and then try 1 60x60x10mm fan, that'll show the benefits.

 

[MAV]

yep, i stacked two coolermaster fans, don't remember the models, dimensions if i recall are 50x50x10mm, rpm of these fans is 5400rpm. After stacking the fans the noise level did increase, but the two fans actually compliment each other as the rpm's on both have increased by between 400 & 1000rpm,the bottom fan is running at approx. 6250 - 6400rpm and the top fan approx. 5818rpm. Air flow with these has improved quite a bit too. Also my idle temp on the cpu is now 4 deg c above ambient, where as before was about 10 deg c above.
regards

 

[Hoot]

Be careful assessing improvement as a function of increase in RPM. Once an axial fan starts letting air slip out the back, the speed will actually increase. Kind of like when your car tires break traction on an icy surface and start to spin. The motor RPMs go up, but but the car does not move. Listen to an axial fan as you slowly bring your hand up to the discharge side. Once it gets close enough to cause the blades to break traction on the air (static pressure), you'll hit a point where the fan speeds up. Ditto on blocking the intake side.

Hoot