Hey, the post that was linked here is mine.The sound was bad in the video, reallife is worst.
But just you know, I contacted lian li and they gonna replace it, so probbably that is not the default sound.
BUT, if it is, it is realy distracting at night in idle (if you are just browsing and stuff), I thought was MB or ram. If you are playing music you not gonna notice it, but once you are in a quite ambient, it is really annoying. Then sound of the fan are a symphony compared to it.
I didnt try what the person above recommended, but pumps in general should be able to run at 100% all the time with no problems.