Question: can gtx 970 run 4k?
Answer: A GTX 970 will still run a large number of games at max settings at 4K without AA at around 30FPS or higher. Considering you don't even want that and will settle for medium settings, a GTX 970 will absolutely be enough at 4K; you should be able to hit 60FPS in most cases at medium settings at 4K.