Overclock.net user and renowned overclocker shamino1978 released a new version of his AMD CPU overclocking tool, adding the ability to overclock and individual Core Complex (CCX) rather than a single core or the entire CPU. Though you can overclock your Ryzen CPUs via the motherboard BIOS or AMD's own Ryzen Master software, neither can overclock an individual CCX.
In case you aren't aware of what a CCX is, it is basically one half of a Ryzen CPU. Each eight-core processor (whether or not all of those eight cores are working) has its cores split into two groups of four cores, and these groups are known as Core Complexes or CCXs. The image above shows a Threadripper CPU with two processors, each having two CCXs for a total of four CCXs across the entire CPU.
It's similar to how the Ryzen 9 3900X and 3950X have two compute chiplets that make up one whole CPU; two CCXs make up one whole processor. In the case of the Ryzen 7 2700, it would be four cores in each group, and for the Ryzen 5 2600, three cores in each group, and so on. These groups must have the same number of cores for the CPU to work, which is why we don't see seven-core Ryzen CPUs and why we don't see Ryzen 5 2600s with four cores in one CCX and two in another.
CCX overclocking could be an interesting way to squeeze a little more performance out of your AMD processor. Though Ryzen 3000-series CPUs are often clocked as high as possible out of the box, previous-gen Ryzen 1000 and 2000 CPUs might benefit from overclocking an individual CCX. When a CPU is manually overclocked, the whole CPU can only clock as high as its weakest performing core. By isolating the weakest performing core to one CCX, you could theoretically overclock the other half of the CPU a little higher.
We're not sure how this would work in practice, but there could be an extra 100 MHz or more sitting on the table for some users, though only for four cores. The CCX with the weakest CPU core can only clock as high as the weakest core, so the seven other faster cores would not go any faster. CCX overclocking is interesting for enthusiasts, but it likely won't improve performance very much.