Threadripper and Epyc are essentially multi-socket-in-a-package. There is an inter-processor link which is analogous to Intel QPI or DMI, it just runs between

Threadripper and Epyc are essentially multi-socket-in-a-package. There is an inter-processor link which is analogous to Intel QPI or DMI, it just runs between dies within a single socket instead of dies in separate sockets. Threadripper and Epyc present themselves as 2 or 4 separate NUMA nodes depending on model. Spreading a single task across multiple NUMA nodes usually hurts performance significantly (often slower than just running it on a single node using fewer threads), but you can run 2/4 separate tasks at pretty much full speed. The new WX processors are a little weird because two of the NUMA nodes have no direct access to RAM at all, they have to ask the other 2 dies to do it for them and pass it over.