Stream does not run smoothly?

Hello so i want to stream but somehow my stream jerky sometimes i stream on twitch with 6000 kps or as it is called again in my pc i have a gtx 1080 an i7 6700k 16gb ram but it still jerky my internet is as stable as i stream games like modern warfare, Rainbow 6 maybe someone knows why this is because the task manager often says that the ram and the cpu are over 90% full

Stream over the graphics card (NVENC). And in what resolution do you stream? Best for twitch is 900p 60fps for streaming.