I have an AMD system with an X570 motherboard sporting an AMD 3600X running Rocky Linux 8.6. This was supposed to be running a newer 5800X, but at the time I tried this, I was on CentOS 7 and the kernel simply did not have the support for the processor.
Because of the oddball way selected features get backported into the RHEL and downstream kernels, I am not sure where we stand on support for the newer Zen 3 processors (the 5000 series). Are these already supported in Rocky 8.6? If not, will they be supported in Rocky 9.0?
According to a quick google for AMD Zen 3 linux kernel support according to Phoronix it is looking good in kernel 5.11. Since by default, Rocky uses a 4.18 kernel like RHEL, then you could enable elrepo and install kernel-ml which is 5.18.
Phoronix link for completeness: Linux 5.11 Is Now Looking Great For AMD Zen 2 / Zen 3 Performance - Phoronix
As for RHEL9, it’s kernel 5.14 from what I read, so Rocky 9 will have the same, and thus will be easier than having to get alternative kernels from elrepo with Rocky 8.x.
The AMD specifications mention that RHEL is supported: https://www.amd.com/en/products/cpu/amd-ryzen-7-5800x#product-specs
The exact version is not specified. Most probably the Zen 3 5000 will run in Rocky 8.6.