This is a good first place to start. Ensure that your power supply is at least 500+W, since the GTX 970 alone needs 145W (without OC).
A common issue that can occur is a bottleneck, but your 8320 shouldn't bottleneck the 970. Go ahead and throw us a reply with all of your system specifications, and maybe we'll be able to find something more concrete to go with.
Also have a look into this optimization guide, it may help. https://steamcommunity.com/sharedfiles/filedetails/?id=385577681
CPUs, perhaps! But my R9 390 disagrees!