XSplit Broadcaster is using some GPU resources even when you choose to use CPU encoder. In fact the GPU resources needed are really critical for a smooth streaming session. Some GPU intensive scenes where the GPU is loaded at full, results in frame stuttering in the stream. Some games requires to set low FPS cap to stream.
Having an additional dedicated GPU for XSplit solves the issue, but XSplit does not allow to choose which GPU to use.
Set the GPU to be used by XSplit as Primary Display (need to hook a dummy monitor to do so). Start XSplit. Set the main monitor/GPU as primary display. Run the game.
Make it possible to choose which GPU XSplit will use.
CPU: Threadripper 2950X 16 cores/32 threads
GPU 1: NVidia RTX 2080 Ti
GPU 2: NVidia GT 1030
Capture Card (For Console Streaming): Elgato 4K60
Monitor (Gameplay): 2560x1440 @ 165 Hz
Streaming Encoder: x264 CPU Slow Preset
Streaming Resolution: 1920x1080 @ 60 fps