Noctua NF-A15 and NF-A14 Cooling Fan Review

backside fanstack 2x NF14 UNL

Bit of Fan History

The NF-A14 is a Square-frame 140mm fan.  A few years ago, 120mm fans were used to get the lowest noise with the highest airflow, and thus better-performing PCs.  Now many cases are coming with 140mm mounts as the only way to improve on this is to go bigger.

Larger fans means more air, so you can let them run a little slower for less noise and still have enough airflow.

As I want my PC to be as quiet as possible when idling (or just browsing the internet and writing reviews), I’m perfectly fine with the fans spinning faster when needed when playing games for instance.

Long gone are the days of 80mm DELTA screamer fans.  Even though they moved air like no other, the noise they produced would also drive you insane and practically damage your hearing.  Additionally, if you messed around in your PC case the Delta fans WILL also remove skin from your knuckles… as I know from personal experience.

Today’s non-blood-drawing fans are much better for the computer tinkering geeks who would have at least a minimum of 2 cuts from either fans or sharp edges of ye-olden PC cases.

So what makes the 140mm fans from Noctua stand out from the crowd?  Well to name a few things that I noticed and thought “hey that’s smart”… First up and the main thing I personally loved the best is what Noctua calls their AAO Frame (Noctua’s AAO Advanced Acoustic Optimization).

I know that they really mean the entire frame (including the stepped inlet), but what stands out is the rubber vibration absorbers on all corners.  One cool thing about them is they can be moved if their placement obstructs anything.

 


These fans already have almost zero vibration but canceling out the last bit with silicone corners is just smart, even small vibrations will go through the entire metal of the case and it WILL find something else to also vibrate and make noise..

Perhaps that why I ordered 2 new hard drives as the old ones have done their time and need replacing and they hum in an annoying way that I want to burn them!

After cleansing my head from evil thoughts and random MoltenCore rants (BE PURGED BY FIRE!!!!), I went on to have a closer look at that AAO Frame.  Included in that is a stepped inlet at the ridges at the rim of the fan.  What you also notice are golf-ball like dimples on the inside of the fan frame, which have a positive influence to airflow and noise (watch more Discovery Channel as they explain stuff like that).  Don’t take my word for it; here’s a quote:

Noctua’s Stepped Inlet Design is an advanced aerodynamic design measure first introduced with the NF-F12 fan. By adding turbulence to the fan’s influx, the Stepped Inlet Design facilitates the transition from laminar to turbulent flow. This measure has an effect similar to the dimple structure of a golf ball in so far as it leads to better flow attachment to the frame, which allows the impeller to suck in more air and hence improves overall airflow efficiency. 

In addition to these aerodynamic benefits, the Stepped Inlet Design also reduces tonal intake noises caused by laminar inflow due to it being transformed to turbulent flow, which produces a more broadband noise profile. This way, the Stepped Inlet Design helps to refine the fan’s acoustic qualities by letting it blend into the background noise more easily and making it more agreeable to the human ear.