recording or streaming

okay so I have a msi gtx GeForce 1080 gpu with intel i7

idk what else I should mention. I keep on trying to record or stream league my my 144 fps always goes down to 50 fps what could the issue be? or is it that I don't have a strong computer? any other games I record like smite or ark evolved works great but when it comes to league its just poop overwatch also runs smoothly