Noctua NH-L9a 2 fans?

Discussion in 'Overclocking & Cooling' started by MuscleNerd, Jun 7, 2019.

  1. MuscleNerd

    MuscleNerd Limp Gawd

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    I'm about to finish my Node 202 build and I was contemplating attempting something, but I wanted to know if this would cause issues with the fans "fighting" each other...I'm not sure how else to word that.

    The L9a uses a 92mm fan that is 15mm thick. I will be trying to overclock my 1700x as high as the system allows me too, but for additional cooling would throwing another 92mm x 15mm fan on top of the already existing one cause any issues ?

    Clearly one way to test this is to try it, i get that, but I'm just looking for some insight form people who have tried this or have done something similar.
     
  2. EnderW

    EnderW [H]ardForum Junkie

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    Not a good idea. You’d be better off getting a single 92x25mm fan. But you’re probably only going to be getting an extra degree or 2 of improvement.
     
  3. MuscleNerd

    MuscleNerd Limp Gawd

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    Can you tell me why it wouldn't be a good idea? What could happen that would be bad? I agree with getting a 25mm instead, I'll just send back the 15mm and get the 25.
     
  4. EnderW

    EnderW [H]ardForum Junkie

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    I think it would probably cause issues with the airflow from the top fan hitting the fins of the lower fan unless you had them perfectly synced up and aligned. Maybe not? There are heatsinks and radiators with push/pull configurations but always with the fans on either side.

    Plus the depth of a fan has a large effect on the amount of static pressure it can generate and I think even if you miraculously synced 2x 15mm fans at best you’d just be “channeling” the airflow through them without actually generating any more static pressure or increasing the volume of air sent through the heat sink.

    So basically I don’t think it would benefit in anyway and has the potential to be worse. A single 25mm fan vs a single 15mm fan will definitely be better at airflow and static pressure (just compare specs) but again, probably won’t change temps much. Look at the large heat sinks that have 2 fans and you can find benchmarks with people running 2 fans vs 1. Even then it’s usually not much difference.
     
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  5. doyll

    doyll Kyle's Thermocouple is HOT

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    Stacking fans without an air strightener between them means the spinning air coming out of first fan simply follows the spinning impeller in 2nd fan with no net gain in airflow. Commercial stacked fans have impellers spinning in opposite directions to solve this problem.

    As suggested a single 25mm thick fan will work much better.

    Also, I suggest you try turning the fan over so it is pulling air out of cooler instead of pushing it into cooler. Reason is air being pushed into cooler hits motherboard turnning out where it it's RAM, back of GPU, etc. and turn up along side of cooler and cooler fan and is drawn back in when it gets above fan. Every time I've tested pushing in vs pulling out with these small pancake / downflow coolers I've ended up with 5-9c lower CPU temps. ;)
     
  6. MuscleNerd

    MuscleNerd Limp Gawd

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    Thank you for the advice and sharing some knowledge. I currently have the system running a single 92mmx15mm and I installed 2 Corsair 120mm AF fans in the GPU bay. My temps are terrible right now, even when I switched the fan around. I'm burnt out on messing with it right now, but tomorrow I will do some more testing to see what if I can get the temps down.
     
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