Tera is really, really CPU reliant. I have the 970 too and I get the same fps as you during some occasions, but I usually float in the low 20's. Cuz my CPU is too weak (FX-6300).
Max settings with 4k downsampled - same fps.
lowest resolution the game supports, lowest settings - around 5 fps more than usual
Then on a 2008 dell laptop that I no longer own (forgot the model, gave it to my sis)
Max settings, can't run.
Lowest settings at 720p - 25~ fps
Yeah.... optimization.