I would stay away from the Nvidia GTX970 line for sure.
Since C1 version 9 arrived, the GPU feature has been very unstable. Not only do you get the "error processing a file" problem with means you can't batch process a file, but there are problems with masking, and layers.
I have had 2 trouble tickets on this issue open for months, and still no fix. And I would have to say, since I started with Capture One way back in the 2005 year range, this single problem has been by far the most problematic.
It's a timing issue for sure, but so far, Phase cannot or will not attempt a fix.
Their only answer, "turn off the GPU". That does fix it, but then you can go to sleep trying to draw a mask or processing out a large number of files.
The Nvidia GTX970 is not a cheap card so I would personally stay away from all Nvidia cards.
Here is my post showing the problem with "error processing a file"
http://forum.luminous-landscape.com/index.php?topic=107751.0Others have also reported this problem. Seems to be mainly an Nvidia C1 intolerance. Windows 10, 8.1 and 7 all show it at least for me.
Paul C