Yes, many users of the Anycubic I3 Mega have successfully used Noctua fans for reducing the noise emission of this 3D printer. In particular, the following three modifications have been reported to work well and make the printer much quieter in operation:

  1. Replacing the hot-end fan with the NF-A4x10 FLX as described here or here.
  2. Replacing the power supply fan with the NF-A9x14 PWM using a custom 3D printed casing for the power supply as shown here or here (also see this PSU cover for the NF-A6x25).
  3. Replacing the motherboard fan with the NF-A9x14 PWM using a custom 3D printed fan holder frame (also see this mainboard fan holder.

Disclaimer: While many users have reported good results, Noctua cannot verify and assumes no liability regarding the correctness of the information contained in such user reports, videos or tutorials. Noctua can generally give no guarantee that a certain fan will work with a specific third-party device because usually, there is no detailed specification regarding fan compatibility and control available for such devices. Please also note that fan compatibility and control can vary from model to model and even from revision to revision, even if the devices are made by the same manufacturer. As a result, it is important to make sure that the information or guidelines you rely on when replacing your fans are applicable to your specific model as well as your specific hardware and firmware revision. Due to the possible issues listed above, Noctua recommends that only experienced users attempt to replace pre-installed fans in third party devices and that special care is exercised when handling sensitive components such as power supplies. Please note that since there are so many devices and most of them lack detailed documentation for fan compatibility and control, Noctua customer support cannot assist you with compatibility issues when replacing pre-installed fans. Please contact your device manufacturer for any questions regarding aspects such as the device‚Äôs pin alignment or fan monitoring and control. The pin configuration of Noctua fans is detailed in this FAQ. Noctua cannot be held responsible for any damage or losses that may occur when replacing fans in third party devices.