[xani_]

Just look at the processor architecture diagram.

But TL;DR modern big processors are not one big piece of silicon but basically "SMP in a box", a bunch of smaller chiplets interconnected with eachother. That helps with yield ("bad" chiplet costs you just 8 cores, not whole 16/24/48/64 core chip). Those also usually come with their own memory controllers.

And so you basically have NUMA on a single processor with all of the optimization challenges for it