I own a Gigabyte 980ti G1 GAMING that is still a rather powerful GPU and I have seen into Pimax 8K specs that Nvidia 980 card would be enough to run it. Then I have seen that the connection require DisplayPort 1.4 that is not equipped on my card since it has DisplayPort 1.2. At present for my 4K TV I am using the HDMI 2.0 port but I know that DisplayPort 1.2 can handle 4K at 60Hz as well. I kindly ask Pimax to confirm that DisplayPort 1.2 is compatible with Pimax 8K in order to run 4K (overall) at 60Hz (120 with brainwarp).
It should be compatible without issue as dp 1.2 supports 4k 60hz and 1.4 is back compatible with the 1.2 displayport spec.
That said, I think a 1070 or 1080 will be a better min spec option for frame time latency and 1% lows. I have posted a new thread testing my 3gb 1060 to see how it handles experiences at close to UHD resolution. @anon23564932
Since the particular screen ratio of Pimax 8K I can expect to handle at maximum 5120 x 1440 (7.732.800 pixels) at 60Hz (standard 4K is 8.294.400 pixels). Due to limited bandwidth of DisplayPort 1.2 I do not know what is going to happen when trying to reach the full resolution 8Kx4K (16.6 million pixels). Provided that the GPU can handle it (maybe a very non demanding game) probably the max frequency will just go to 30Hz (that would be 60 due to brainwarp effect). Personally I think that in any case the new coming Volta GPU is the only answer to every problem.
Good news they will have support for dp 1.4 (tho prob need a card to support)