Well a waterblock compatibility will depend on the design of the PCB. since reference PCB'have a different layout then non reference. Since the Galaxy card you speak of has a 680 PCB for the most part then you might could get a 680 water black.. But do some more reading on it before you quote me on that.
Yeah, I wasn't sure if it's a full 680 PCB or not, which has made research into compatibility difficult for me.
Thanks, I will keep looking into it (though I guess that goes without saying, lol).