Heatsink Fans North/South vs East/West?

Is there any specific reason why it is most commonly recommended to point the heatsink fans east and west (horizontally) rather than north and south (vertically)?

I'm in a bit of a "will it fit" bind, and if the cooler i purchase doesnt fit it seems like it may fit with fans going north and south (i think the south fan is a pull and the north is a push, not sure). This actually sounds pretty ideal to me, since I have a huge fan at the top of my case blowing out. Anyone with the logic on why these are typically pointed horizontally?

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  1. Best answer
    Well I guess there's 2 concerns. The first being intake air, the second being exhaust. Many cases do not have top fans, but since yours does the exhaust isn't going to be an issue. So, the intake then. Where does this air come from? Probably, it's going to be right next to a GPU, and GPUs tend to run very hot - 60-90C, depending on the model. CPUs generally should be running below 70C max, so naturally if you're sucking in this hot air that's not a good thing.

    So, it really depends on the set up. If your GPU shoots air out the back of the case, then it shouldn't be a bit issue. Otherwise you might consider a couple options. First one is a shroud to help the CPU fan only suck in cooler air/block the GPU air. You could also possibly mount a side fan to either suck out hot GPU air, or blow cool air in - I found that blowing on the GPUs helped them keep cooler temps, but I would assume sucking the air out would overall help the case temps be lower. You could also potentially have the side fan blowing in, but make a shroud to give some pure outside air directly to the CPU fan.
  2. ^1 Wolfram23
  3. I've asked the same question of prolimatech tech support who responded that their testing has shown a 2-3 c advantage w/ fans placed horizontally
  4. Typically the air flow in a pc case is bottom/front to top/rear. The fans at the bottom/front of a case are intake fans and the fans at the top/rear are exhaust fans. That's the main reason most cpu heatsink configurations are for airflow from front to rear. It takes advantage of the typical airflow.

    Scroll down to the bottom of this web page to see an animation of typical airflow in a modern case:

    I took it a step further and created a wind tunnel effect in my personal pc:
  5. Best answer selected by Katiklysm.
  6. nice site and build jonny. All of the info provided was very helpful, thanks guys.

    I think I would lean toward North/South if I had an External Exhaust GPU, but that is a good concern- that my GPU is probably putting off 60 or more C on average.

    I *do* have a side fan mounted- very happy with the CM Storm Sniper Black Edition as it has covered a lot of these airflow concerns that I would not have considered in advance.
  7. JackNaylorPE said:
    I've asked the same question of prolimatech tech support who responded that their testing has shown a 2-3 c advantage w/ fans placed horizontally

    Here is an article indicating heatpipes shoud be oriented so they span front to back and fans blowing up towards the top of the case...scroll to the bottom

    It seems the direction of heatpipes plays a big part in how easily the fluid moves within them, thus impacting the cooling.
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