Review on Noctua NF A4X20 FLX Premium 40X20Mm by Chef Buntiloy

Very high quality but very low throughput of 5.5 cfm. I tried them out in an Arista switch to replace my existing powerful but ridiculously noisy Sunon fans. They couldn't get the job done. The processor temperature has exceeded 50 degrees. I changed d to the pwm version which outputs a little more cfm but still not enough. The overall airflow was significantly less and the temperatures increased by 15-25 degrees Celsius. Just not enough air. My solution ended up leaving the original fans and grounding the PWM input to slow the fans down to their minimum speed of around 25% (the CLI only allows operation up to 30%), and some creative blocking and sealing work perform ensure that the hottest component has enough. draft. Cooling these units is brute force due to the lack of engineering in the design and a few simple modifications and changing the airflow from back to front resulted in temperatures in the range of 31 to 39 degrees C instead of the 41 to 49+ the Noctua offers. 27 to 34 were initial temperatures with fans at 60 percent and an outside temperature of 21 degrees. These are really good fans, but make sure your hardware can handle very low airflow. I also wish they came at a reduced price without all the accessories. It's great to have all the options if you're only buying one or two fans, but if you need 3, 4, or 6 (in this case) you end up getting $6 or $7 worth of stuff for each remaining fan. have no need. I also wish they would provide a 4 pin pigtail header for the PWM version so you don't have to cut off the solder fan header when installing. I give them 4 stars because they are really good fans and well documented. (in other words, since you have all the data, if it's too anemic to work with, it's your own fault). I would give them 5 stars if the top speed is around 20fpm and the option to slow it down if needed. In my estimation, they probably won't be enough for most applications - the noisy fans used in many rackmount devices put out up to 65 cfm.