If you have a gtx 980 ti I would say not to worry too much. Those games are pretty unoptimised at the moment ad also bare in mind that there is no full DX12 gpu (in terms of features supported) on the market yet. I have an MSI R9 390 and I have come up to the conclusion that Nvidia has optimised very well on DX11 while AMD was a bit behind (now it catched up in most cases) while now, Nvidia gpu's are just not built around async compute (AMD Mantle helped develop DX12 so it is natural that DX12 games are currently more optimised for AMD, Nvidia just didn't have the time to optimise properly, the developers are also new to working with DX12 so it will take some time).
Also, those games seem to be poor ports (especially Quantum Break) and such games are not worth buying (not even playing) in their current state.