[memoriuaysj]

bus wires. you can route only so many of them on a motherboard.

it's why GPUs have their memory chips in a circle around the GPU chip.

[foota]

Wouldn't this be the limiting factor moreso for overall throughput, not per core? I believe with Zen 4 for instance it goes through a central memory controller.

[memoriuaysj]

sure, but you can have more memory controllers (I/O dies), like threadripper