https://www.anandtech.com/show/15137/amd-clarifies-best-cores-vs-preferred-cores AMD in a blog post earlier today explained that there is no 1:1 correlation between the "best core" grading system displayed in Ryzen Master, and the "preferred cores" addressed by the Windows 10 Scheduler using CPPC2 (Collaborative Power and Performance Control 2). Deployed through BIOS and AMD chipset drivers, CPPC2 forms a middleware between OS and processor, communicating the system's performance demands at a high frequency of 1 ms (Microsoft's default speed for reporting performance states to processors is 15 ms). Ryzen Master, on the other hand, has had the ability to reveal the "best" cores in a Ryzen processor by ranking them across the package, on a CCD (die), and within a CCX. The best core in a CCX is typically marked with a "star" symbol on the software's UI. The fastest core on the package gets a gold star. Dots denote second fastest cores in a CCX.
"Ryzen Master, using firmware readings, selects the single best voltage/frequency curve in the entire processor from the perspective of overclocking. When you see the gold star, it means that is the one core with the best overclocking potential. As we explained during the launch of 2nd Gen Ryzen, we thought that this could be useful for people trying for frequency records on Ryzen," reads the AMD blog on the discrepancy between Ryzen Master "best cores" and CPPC2 Preferred Cores. "Overall, it's clear that the OS-Hardware relationship is getting more complex every day. In 2018, we imagined that the starred cores would be useful for extreme overclockers. In 2019, we see that this is simply being conflated with a much more sophisticated set of OS decisions, and there's not enough room for nuance and context to make that clear. That's why we're going to bring Ryzen Master inline with what the OS is doing so everything is visibly in agreement, and the system continues along as-designed with peak performance," it adds. "Best cores" and "preferred cores" are hence both "right." The former refers to a physically high-quality core, while the other is more "circumstantial", for better performance.
Hopefully this explanation provides some clarity