Depends on the core utilization of the game you want to stream/record.
With 10 real cores, you should be able to use the x264 preset "slow"in most scenarios.
I got an R7 1700x@3.8GHz. With my 8 cores / 16 threads, I can use 720p 60fps x264 "medium" and even "slow" preset when recording games that aren't very CPU hungry, or when dropping video fps to 30.
For 1080p 60fps recordings you might need to drop the preset to medium or fast.
At streaming bitrates (2500-6000kbit/s) 1080p 60fps will look shitty at games with a lot of motion and details, no matter if the preset is very fast or slow.