Ryzen

AMD Ryzen 9 3900X 12-Core Processor (1 Socket

Internally it contains multiple die's so L3 cache is shared between all dies. This cause additional memory latency when memory access crossing dies.

https://www.servethehome.com/amd-epyc-infinity-fabric-latency-ddr4-2400-v-2666-a-snapshot/

Threadripper has two work modes. Your bios sets it in Unified Memory Access Mode.

Possible to switch BIOS by setting “Memory Interleave” to “Channel”