To elaborate, liquid coolers, especially closed loop coolers such as the Corsair H150, for the last many years are not like they were when they first came to the market. Leaks are extremely rare, and the liquid is not electrically conductive. Some companies, such as Corsair, also warranty all components in your PC against damage caused by a leak. Newer models also feature more flexible hoses as well to make installation easier and to reduce stress which helps prevent leaks.
Yes the pump is a much more complex item than a heatpipe so it can malfunction, but liquid coolers from reputable manufacturers have longer warranties than are typical for electronics for that reason. Corsair and Enermax have 2 year warranties, Cooler Master and Gigabyte 3 years, for example. Heatpipes can also malfunction and leak their coolant, rendering them ineffective, and that is the most foul smelling substance you will ever smell if it does happen...did to me way back when I had a tower cooler, the Xigmatex HDT-S1283, on my Athlon64 6000+...
Also it has to be said that unless you are a professional user, the 3950X is extreme overkill. For gaming an 8 core CPU is plenty fast, far less expensive, and easily air cooled, though the silence and performance in warmer ambient environments afforded by liquid is a benefit to anyone, especially considering the fact that AMD's Turbo algorithms shoot a lot of voltage to the CPU, in excess of 1.4v, which generates quite a bit of heat, and temperature is the prime factor in determining how fast that Turbo speed is.
