I'd suggest dropping the H100i from your shopping list and replacing it with the Swiftech H240x..... more cooling, 1/6th the noise. Then use full cover water blocks fore the cards .... cooling the GPU with H55s will still leave you handcuffed by the air cooled VRMs.
2 x $30 for the G10's
2 x $60 for the H55s
1 x $100 for the H100i
That's $380
Think about it .... 2 x 120MM fans at 2700 rpm for a CPU (Haswell / DC = 84 - 130 watts)
And only 1 x 120mm @ 1700 rpm for 780 (255 - 300 watts) ? .... A 120mm radiator / fan at 1800 rpm provided about 80 watts of cooling.
Swiftech H240-X = $150
2 X EK water full cover water blocks @ $115
1 280mm radiator= $65
So for $65 more you could have true water cooling at a helluva lot less noise...