Maybe it's their friends Nvidia have asked them to push you all to G-sync. ;p

Seriously though, the coding in this game is beyond weird. I have Crossfire R9 290, 64GB RAM, SSD & i7 4820X (quad core seen as octa) and still drop to 25 frames per second in Mor Dhona. On the initial character screen I get closer to 400fps. Even worse, the aforementioned 25fps can't be improved by disabling graphics niceties. It isn't maxing my CPU either.

That said, DX11 made it a different game altogether.