A Ryzen 2700X coupled with a 1660Ti is a good balanced setup. Don't fool yourself into thinking it is the most powerful system out there. It is not. It is an above average gaming system compared to todays 3rd gen Ryzen and i9/i10 systems today.
Now what I am going to offer you is experience using that exact CPU as I own one. Last year, I used a Ryzen 2700X and GTX 1070 in a single PC gaming/streaming setup. The results were good and were capable of producing 1080p@144FPS at x264 medium preset with the first person shooter games I played. It is still a very good gaming/streaming setup to use for single PC streaming/gaming setups.
I no longer use that setup and have replaced it with a dual PC streaming configuration. Why? Because what you will eventually find is that the CPU load along with x264 and all the other services and applications that you run will be close to 80% CPU utilization. In my case, I didn't care for that level of utilization and wanted high 200FPS in the games I was playing.
So I split the CPU load across two PCs. Now, I have 25-30% CPU utilization on the Ryzen 2700X dedicated x264 box, and 35-50% playing games on an i9-9900K. NVENC new wasn't available back then.
In your case, you are eventually going to find out that you will reach heavy CPU utilization as you play demanding games along with trying to do x264 encoding. This is the reason why I suggest that you reduce resolution to 900p, set a decent bitrate up to 5Mbps, and use NVENC.
That's all I am going to say of this. So please, do not contact me any further. You got what I had to offer.
Have fun.