I dont think thats correct. x264 wont be able to efficiently use 12 threads on a four core with 8 threads in total. x264 shouldn't use anywhere near the maximum number of threads available to the entire system. You have to leave threads available for system services.
This is how I think it works...
By default, x264 creates 1.5 times the number of cores to be the number of threads it uses in the system. I've seen this 1.5 multiplier thrown out in some forums (I could very well check the open source but am too lazy). Assuming this multiplier, on a 4 core CPU, up to 6 threads can be used for x264 processing. The two thread slack is so that other services like O/S and your application can run beside it.
Assuming the 1.5 multiplier, this leaves x264 devoting these number of threads from the CPU limitation:
1 core, 1 thread max out of 1
2 cores, 3 threads max out of 4
3 cores, 4 threads max out of 4 (rounding down)
4 cores, 6 threads max out of 8
5 cores, 7 threads max out of 10 (rounding down)
6 cores, 9 threads max out of 12
7 cores, 10 threads max out of 14
8 cores, 12 threads max out of 16
BUT, this depends on what else is running on your system
If you are playing a game that needs 2 threads minimum on a CPU that only has 8 total threads, you devote 2 threads to the game, at least 2 threads to the O/S services and OBS studio, and the rest to x264. That leaves you with 3-4 threads to be used for x264 processing.
What those 3-4 thread setting is will depend on what alias named (faster, veryfast, etc) you choose.
The higher you move up in the OBS drop down box, the less threads are used for x264. Consequently, when you run your other applications like a game, they get the remainder. This may seem to imply that you should load all your applications up first before launching OBS Studio....
In a dedicated PC streaming box, there is nothing wrong with having high CPU usage utility - you want that. Conversely, if you are getting 50% CPU usage and getting the right results, you got an overkill of a CPU.
What you are probably afraid of is that a high CPU usage means your system is overheating. It will generate more heat, but thats where you need to monitor it and put on appropriate cooling apparatus.
If you are concerned about high CPU usage, you have two choices:
1) Buy a higher end CPU with more cores and threads
2) Fiddle with the CPU preset and bitrate
If #2 doesn't work, you have to do #1.
Also, in your particular case, you don't have NVENC on your GPU. You can buy a GTX 1050 to avoid having to worry about CPU usage because all of the encoding will be done on the GPU encoder chip. That will leave all 4 cores/8 threads for you streaming PC to utillize and you should see the CPU usage drop.
