I have an i7PC with Geforce GTX 980ti gpu, 32gb fast RAM, upgraded to 17 because of the promise of smooth playback. Feel I have wasted £50 as it is no better than in 16 still choppy.
I don't see a question in your comment, but if you're asking why your video is not playing smoothly -- Open your video source clip in the free download MediaInfo. In MediaInfo, set View to Text and then copy the text that it generates and paste it to this forum.
Once we know more about the media you're working with we'll better be able to troubleshoot your issue.