What is the difference between Nickel and Copper?

So-called ‘Nickel water block’ is still a pure copper water block, but plated with a layer of nickel. Performance wise the nickel plated water block is identical in performance to non-plate (bare) copper water block.

What is a Full Cover (EK-FC) water block?

A Full Cover water block’s main advantage is that it cools all heat generating components – GPU, RAM IC and VRM by a single cooling unit and in a single coolant pass.