I have it on a 7200rpm WD Blue, No stutters. Your specs seem fine. It has to be something else. Make sure you have the latest drivers, clean of viruses, and nothing running in the back ground. How long since you refreshed your windows?
Your specs are close to mine. Ultra settings around 90FPS average on my specs for reference all stock clocks playing smooth.
I5 4690K
8GB Ram
970
HDD