The Thermaltake Water 3.0 Ultimate is a true high-end liquid cooling system. It beated (by far) one of the most high-end liquid coolers we tested to date. Even with its fans at low speed, it maintained our processor 10°C colder than the Water 2.0 Extreme with its fans at full speed.
The only drawback of the Water 3.0 Ultimate is its compatibility: you will need a case that supports 360 mm radiators, which most likely means a high-end, and thus expensive, case.
If you have a compatible case and need extreme (better said, ultimate) cooling performance, the Thermaltake Water 3.0 Ultimate is an outstanding choice.