TLDR; on 1440p+ with 3000 and newer Ryzen CPUs, limiting physical cores to your fastest CCD (chiplet) with good cooling will gain you higher frequency, especially with PBO / Auto OC.
As you might already know that forcing physical cores (like in game settings and process lasso to not use the logical SMT cores) can help performance but if you're running a CPU like the 3900x, you can actually squeeze even more by limiting yourself to your first 6 physical cores. Let me explain:
The 3900x has two chiplets inside of it. A good chiplet and what we call a "meh" chiplet. The first 6 cores / 12 threads of the 3900x has a much better bin than the second chiplet. When there's a lot of work to be balanced across multiple cores, the CPU will lower it's clock speed to offload to more cores and the fast chiplet will actually slow itself down to match the "meh" chiplet in many cases. Also the workload spread across more cores can generate more heat and create a lower frequency boost. In a CPU intensive game like Tarkov, the 3900x can actually run slower when you're allowing it to use both chiplets and more cores. Here's the solution:
By using process lasso or simliar and disabling all cores except 0, 2, 4, 6, 8, and 10 on a 3900x you are effectively allowing the faster chiplet to take hold and it should actually boost faster. There are other important factors because Ryzen CPUs thrive off of good cooling so things like PBO, Auto OC +200, and other methods (like undervolt to improve thermals) that allow your frequency to go higher will pick you up a couple hundred Mhz of performance. Mix that with some good ram and you can see some decent gains. The difference on my 3900x is actually going from 4.25 Ghz to 4.4 Ghz in my case means a lot when you're becoming CPU bound at 1440p.
With other high core Zen 2, mileage will vary dependent on chiplet core count and binning. Cooling is super important on these CPUs because the closer they are to 60c, the faster they run. This is why undervolts and limiting EDC with PBO can actually boost faster than just letting the CPU have as much power as it wants. This isn't a super boost and it probably won't fix any major problems if you have them but I hope this helps if you like to make the most out of your hardware. Also, this trick is only useful to games that care about single threaded performance and aren't super optimized to higher core counts so it may help in a few other titles.
