Going above 550W doesn't buy you *anything* unless you plan to SLI the 1080s. In that case, go 750-ish.
Never, ever do 4 sticks of RAM unless you are max populating what the board can hold. 4 sticks is actually a hair slower than dual and does nothing but generate more heat since they're jammed together.
Water cooling is a waste. If you spend 3x more on water you *might* get another 200MHz OC, which on a respectable 4.4 OC is a whopping 4% gain.
You could look at 34" 1440p monitors as well.