Nvidia doesn't appear to have seen fit to make DSR work on Linux. When I was last thinking about this, I saw suggestions to mess with viewportin to get the same effect, but that didn't end well - resampling was terribly bad quality (nearest, I think). Also, when I went all the way to 4K (on the theory it might make resampling to 1080p easier), the only bit that got sent out to the display was a narrow band at the top.
Anyone have any ideas on how to get supersampling working with arbitrary games? It's Arch Linux, a GTX 960, and Nvidia proprietary drivers, if any of that helps.