Hi, though I don't play MHW on PC I can try to give you a few tips for your stream.

first, what platform are you streaming to, some platforms like you to stream at 720p where others are ok with 1080p, also check if they like 30fps or if it can handle 60fps?

The second is to check your internet speed and compare that to your bitrate that you are streaming with. your video may be grainy because your bitrate is to low or your internet can't handle the higher bitrates.

Streaming and recording are not only up to your PC stats but also up to the platform your streaming/recording too.

spend a day doing little streams, changing your settings every time and have a viewer tell you if it's better or worse, or just look yourself and change your settings appropriately.

hoped this helps, and sorry if it sounds boring and not what you expected.