I'm using two of these as coolant recirculation pumps to cool some servers, switching between the two so that neither one is run continuously. They've been reliable so far, but they are very loud! Actually, it's not so much the volume but the frequency, there's a constant high pitched whine when they're on. I bought these partially based on some other reviewers who said they're quiet, but perhaps their use cases were different. I don't think it's any defect, as they both sound exactly the same.
Rating:
[5 of 5 Stars!]