The MSI Sea Hawk is probably the fastest one. It's not just the factory overclock, but also the cooling necessary to promote higher Turbo Boost clocks. The MSI Sea Hawk comes with a Corsair all-in-one water cooler.
Quote:
"The focus of our evaluation was the MSI GTX 980 Ti SEA HAWK. It performed faster, overclocked to highest frequency we have seen on a GTX 980 Ti yet, and achieved the lowest temperature by any GTX 980 Ti."
"While outperforming the competition in-game, the power draw was also significantly lower than the MSI GTX 980 Ti LIGHTNING. This video card was performing better while using less energy and had the lowest temperature we have seen on a GTX 980 Ti. You can't buy a faster, quieter, colder GTX 980 Ti than the MSI...