For streaming specifically, all your extra cores can be used to increase CPU encoding quality which is generally far better than GPU or capture card encoding.
The best value is a 1700 overclocked to match an 1800x or better, if you don’t mind doing that. But even stock it’s a lot better than the Intel for streaming.
GamersNexus is a very reputable hardware testing site:
Streaming on the 7700K can work. If it must be done, it could be – it just depends on a few items of varying import:
The streamer will have to sacrifice stream quality. This can be done by moving from “Faster” to “Veryfast” or “Ultrafast,” in one part.
The streamer may w ant to set process priority for OBS, or play with affinities. This begins exiting “works well out of box” and entering “enthusiast project” territory rather quickly, but will help. The downside is that there’s some for the streamer-side framerate.
More resource-intensive games will have more difficulty coping with process de-prioritization (or streaming in general), as resources get assigned to OBS rather than strictly to the game.
Lowering bit-rate, e.g. to 4Mbps, can help further lighten workload on the CPU, but does so at the cost of output quality.
In this way, Intel’s CPU has now become the “project car” product. AMD Ryzen started its life as a project car – the product you buy because you’re OK with being under the hood a few hours a day, just to get the thing running perfectly. Now, with Ryzen’s initial launch issues somewhat smoothed out (but not completely), the CPU is holding well in streaming performance with minimal out-of-box tweaks. To get the 7700K to hold performance, we need quality tweaks, overclocks, and other “under the hood” modifications.
TLDR Ryzen 1700 is what you want for streaming unless you use a separate capture system.