Question about Corsair Graphite 780T

Installation above: Yes.
Front: Yes, but only if the drive cages for the 3.5" discs are removed, which can be done by loosening screws.

I have installed a 38mm thick EK-CoolStream PE 360 at the top, the fans for it are installed above the fixings between the radiator and the cover grille (pull set-up). The screws therefore go from fan->bracket->radiator. The radiator does not overlap with the mainboard, only the connections to it. The 26mm thick radiator of the H110i GTX should therefore easily fit.