If your i3 has QuickSync enable it. If you don't know find specifications for it on google or let us know and we'll return with the answer.
Regardless if you have QuickSync or not these are roughly what settings I use.
Recording resolution is 2560x1440 with downscale to render at 1280x720.
Bitrate is set to 3000kbps for live streaming. For local recording I set it to 30,000kbps
If you have cpu encoding enabled set it to "normal". If games lag increase it to "faster" or "fastest".
Framerate is 45 for livestreaming and 60 for local recording.
Keyframes for OBS to stream to twitch should be locked down to one option. My keyframe interval for local recording is 5.