That's 1x I/O chip (kind of like a router), and 8x chips, each of which has 8x cores on it. Total for 64-cores / 128-threads across 8-compute chips, talking together through a central 1x I/O and Memory chip.
The I/O chip is the biggest for reasons: 1. Its made on a cheaper process. 2. It has worse performance than the compute chips. 3. Its required to be big because driving external I/O requires more power.
So the I/O chip can be made on a cheap / inefficient 14nm process, while the CPUs can be made on a more expensive 7nm process (maximizing clock rates, power-efficiency). The big I/O ports are going to eat up a lot of power regardless of 7nm or 14nm process, so might as well save money here.
For EPYC, AMD is using nine chips: https://images.anandtech.com/doci/13561/amd_rome-678_678x452...
That's 1x I/O chip (kind of like a router), and 8x chips, each of which has 8x cores on it. Total for 64-cores / 128-threads across 8-compute chips, talking together through a central 1x I/O and Memory chip.
The I/O chip is the biggest for reasons: 1. Its made on a cheaper process. 2. It has worse performance than the compute chips. 3. Its required to be big because driving external I/O requires more power.
So the I/O chip can be made on a cheap / inefficient 14nm process, while the CPUs can be made on a more expensive 7nm process (maximizing clock rates, power-efficiency). The big I/O ports are going to eat up a lot of power regardless of 7nm or 14nm process, so might as well save money here.