I've been using the same pump for a number of years now; An 18W DDC that I bought from Danger Den back when I had my C2D E6600 machine. I've been running it at maximum voltage from the 12v molex that entire time and I it occurred to me a few months ago that I could be getting close to the MTBF time of the pump and that I should keep an eye on it, so I set up events in Speedfan to track the pump RPM value and to beep if it drops below 1500 and to shut the system down if it drops below 100 RPM more than 5 times in 15 seconds. I bought a new case recently (CM Cosmos II) for a planned rebuild of my system and loop, and at the same time bought some new WC gear from Aquatuning, including a new DDC; just in case. UPS delayed my delivery by a whole week, so the stuff from AT just arrived today and just now my Pump RPM-drop event triggered; and then my system started beeping at me and began to shut down. I won't get to install the new pump until wednesday due to work, which sucks; but it struck me as really spooky (and fortunate) that my old pump would fail on the very day that the new one arrives. Since I'm not superstitious, I'm going to chalk it up to my amazing planning skills. I realised later that with an MTBF of 50'000 hours for a DDC I'm actually probably a couple of years shy of the pump's typical lifetime!