Sorry, It won't work. You need more CPU cores. Unlike DirectX games using shadowplay, which uses your GPU, OBS encodes and compresses completely on the CPU. It needs as much power as you can give it.
I use OBS and I have a 4C8T running at 4ghz+ and I can sqeek by at 1080p45. If I was to go 60fps, I need to drop it to 900. I for a long time, pondered getting a Xeon, so I could get 6Cores. I mean, you might be able to pull 640p30.
That realization aside, what settings are you needing? You need to Run OBS, Run your game, create new profile in OBS, select where the video source comes from. Some games use different pipelines. I'm not a Dota 2 player, so I don't know. Start streaming to Twitch, and see if your stream is working. You might have to grab the stream from the monitor, instead of the GPU. It's a trial and error thing the first time. After that, you know what to set your profile as. Then in settings, make any adjustments you deem necessary. Higher Bit rate audio will use more bandwidth and CPU. Higher Bit Rate Visual Compression will result in better video quality, but kill your bandwidth. It's all a balancing act. I went to Youtube and watched "How To" videos when setting mine up, and it's still a bit different game to game. Basically, the software is really good at what it does, but it's a nightmare to set up.
Realize you also need cores to game. So giving OBS 2 cores will mean you are gaming at 1 fps.