I’m planning a high-end desktop build with 256 GB of memory (finally the 64 GB unregistered modules are available) and either an Intel 285K or an AMD Ryzen 9950X (or 9950X3D) CPU, so far I don’t have a strong preference for either CPU vendor. As far as I have seen, the generic consensus is that Intel is typically better supported by Qubes than AMD - but I’d still prefer to have a board which has been successfully tested with Qubes before.
The main requirement is that the base system works in a reliable way (including onboard graphics) and that it is able to forward PCI devices (such as USB, Network, SATA) to Qubes domains without annoying issues/instabilities. Suspending is not really required for that machine (but it would be nice to have).
Regarding the Intel platform I didn’t find much in the HCL at all, there are two Z890-based boards (ASUS PRIME_Z890-P_WIFI and Asus Proart Z890 Creator WIFI) but these are only tested with Qubes 4.3 (but not with the stable 4.2 release), not sure if there are any showstoppers with running 4.2 on this kind of hardware. Also from these two boards, the ASUS PRIME_Z890-P_WIFI seems to have some significant issues with PCI bridges and the Asus Proart Z890 Creator WIFI is overly expensive, I don’t really want to spend ~500€ on a board if a cheap B860-based board for ~150€ has all the hardware features I need.
For AMD there is at least one report that the MSI X670E Tomahawk is working with Qubes 4.2 (see AMD Ryzen 9 9950X with MSI X670E Tomahawk).
Using stable Qubes 4.2 (probably with kernel-latest) is definitely preferred but it may also be acceptable to start with 4.3 with the assumption that it will eventually become stable in the months to come.
Any recommendations are welcome.