Noctua NA-FK1 Redux, Second Fan Upgrade Kit for NH-U12S Redux Cooler

Not much to say here. It improved the cooling on my 9700x about 5C. Not bad for the price, and came with everything needed to install. If I had to critique one thing it would be that the vibration dampeners included are thicker than what came with the cooler.

I got this little kit to replace a 140mm fan on a G2 so it would clear my ram. It fit on the G2 and works nicely. No complaints.

The NH-U12A Reux is a great cooler. The second Fan is easy to attach and makes a great cooler even better!

Quality fans. Yes they are a little pricey but you know what you’re getting with reliability. Better than those stupid RPG LED fans!

If you want a heavy duty and solid Quilty fan you can't go wrong with Noctua brand.

So as others have stated I used this as an add on fan for the NH-D15 cooler. My ram was too big to fit the 140mm fan in a push configuration in my meshify C case so I had to set my 2 larger fans in a pull pull configuration as seen in the photos. That was fine for a while with no problems until I upgraded to a 12700k and started to dabble in overclocking it. The cpu puts out a ton of heat when overclocking starts and before my cinebench r23 would quickly push my cpu to 97c and hold steady at that temp until the run completed. After throwing in this fan without changing anything else my temperature dropped the 89c under load with r23 pulling 230 watts with my nh-d15. That’s an incredible 8c drop and way more than I was expecting. Obviously ymmv depending on your use case. I already had 7 fans in my case as it was and this would make 8 and I wasn’t expecting this much of a difference but I think adding the push fan made the difference.The fan itself is incredibly quiet and my system doesn’t sound any louder than it did without it. It seems to be well built and is doing the exact job I was hoping it would do. 10/10 thank you Noctua.I’m considering replacing my other cheaper fans with more of this one because of how quiet it is. No RGB but these fans really do work.

I bought this fan in addition to the NH-U12S cooler, with the single fan the cooler comes with my temps were around 38-45 at idle and around 60-65c under load. With this fan installed in a push-pull configuration, it dropped to around 35-40 at idle and around 50-60 under load. So for $16, it did help to drop my temps a few degrees, which i think is well worth it.It was just as easy to install as the original fan the cooler came with, the only really difference was that the anti vibration pads on this kit were a little thicker than the original fan, but this didn’t make any difference in the install or operation.Noise wise, it is a slight bit louder with this additional fan, but not enough to make a noticeable difference and bother me. It does come with adapters to reduce the noise if you need them, but it’s at the cost of fan speed, so i ended up not using them.Happy with my Noctua products so far, and ill for sure be using them again for any future cooling i may need

The Noctua NA-FK1 Redux Second Fan Upgrade Kit made a noticeable difference in cooling performance, lowering my CPU temperature by about 3°C. While this might not sound like a huge improvement, the real benefit comes from the push-pull configuration, which significantly boosts airflow. With two fans in place, I’ve seen better cooling efficiency, especially under load.The kit also includes 3 fan cables, which are a great bonus for future upgrades or use in other parts of your computer.Overall, I consider this a solid upgrade. While your mileage may vary, adding a second fan to your CPU cooler provides better airflow and cooling. Noctua is well-known for their high-quality, reliable performance, and this upgrade kit continues that legacy. If you’re looking to maximize your CPU cooling, this is a worthwhile investment.