Stacked 140mm exhaust fans

Hardware Hub Cooling
1

I'm doing a new build soon in a Define S case that would have a 420mm radiator on top and a 280mm radiator in front and I plan to install both radiators in a push configuration. This yields five static pressure intake fans with a possible sixth fan (airflow type) in the blank spot in front on top of the 280mm rad. The issue I'm trying to determine is exhaust. I know already that six intakes and one exhaust is well into the positive pressure side of the spectrum, but I'd like to increase the exhaust output to remove more of the warm/hot air sitting inside the case, preferably without having to resort to a noisy high RPM fan.

A couple years ago OC3D did an interesting (though highly impractical) mod with an H100i where Tom took 40 120mm fans and stacked them so that there was 10 fans on each fan mount on the H100i radiator. His experiment was of course in the name of science but the overall result was that he was getting CPU temps in the negatives (Celsius), presumably because of the insane airflow.

There was quite a bit of fan noise in the video, however 40 fans redefines extreme in my book.

My question to the cooling community is this: if I were to stack 2x 140mm airflow fans for my rear exhaust port would there be any significant increase in air flow over a single fan? Say, 30-50%?

2

Watch the video again all the way to the end.

3

you would get no benefit from stacking any fans, at all..

4

Not worth it at all. Besides, I'm pretty sure this was a gag type video :)

5

<= f*ck all difference. All your doing is starving 1 of the fans and making unnecessary noise.
You do realise TTL's vid was a joke yeah...
Just grab a decent quality fan if you want better airflow.

6

Stacking fans used to be a thing over ten years ago.

Long story short, you would not increase airflow - at least not in any meaningful manner. When you stack fans, you are essentially feeding the same airflow from one fan to another.

7

Thanks for the replies everyone. I had a feeling there would be no benefit but it's always good to get feedback. I was remembering from physics that if you combined two separate airflow streams that the velocities would add together, but it makes sense (especially now) that this wouldn't apply here since this is technically one air stream.

8

stacking fans makes it woosh really loud though, cool if you wanna do a fighter jet case mod... >_>