I don't hear it at all. The GPU and case fans are louder. But they're not loud either. I love this cooler. But it's BIG, so 2 things to consider
1) If you want to use both fans, measure the height of your RAM sinks. You could have an issue with installing the front fan (I do, but it's not needed - no heat issues)
2) Since you have the Enthoo case with a nice big window it will fill 25% of the case and not look as nice as a water block for instance.