try whit one 680 first and see how it will work for you, they are expensive i guess ( dono what they cost your way ).
and i would drop the H100 since your gona do wc on the vid card.
mabye do a 240 or a 360 rad in the top ( inside ).
hdd try ssd for os and game and hdd for storage ( cheeper per gb then ssd ( my opinnion ) )
and im whit "who_farted?" on the memmory.
i recomend a reservoar that "block" the air from going to the highest point in the waterloop ( witch is the radiator ) and that way you will reduse the cooling.
mabye do a push/pull on the rad?
go over and watch some of the builds in this link :
http://rog.asus.com/forum/forumdisplay.php?40-Case-Modding-amp-PC-Build-Picsmabye you can get an idea on how you can set up yours? ( not thinking of modding out the case and so on ) but for an insight of how it can be done in the watercooling way
🙂