makes less noise but can still hear it well

Alarma Total recommends this product for various HIK vision NVRs, including the type I have.
The difference in sound with the original fan is really enormous. From annoyingly hard to perfectly tolerable.
I cannot yet say with certainty whether this fan actually cools sufficiently. The specifications indicate that it moves slightly less air than the original, but the NVR does not seem to get very warm!

+ Much quieter than original fan

â Slightly less capacity than original fan!

It's quieter from me, it could be even quieter. But that may not be possible.