Champion stutter

Hi, guys! I have a problem. When i want to watch a stream or to listen music on my second monitor which is connected to igpu (i5 6400), my champions are stuttering like in video. My main monitor is connected to an rx 470 and 1st monitor have 1080p 60hz and 2nd monitor is 1280*1024 75hz. How can i fix that? P.S: Sorry for my bad english!