As much as I can understand a Zen 5 CPU core can run two AVX512 operations per clock (1024 bits) + 4 integer operations per clock (which use up FPU circuitry in the process), so additional 256 bits. At 4 GHz, this is 640 GB/s.
I suppose that in real life such ideal condition do not occur, but it shows how badly the CPU is limited by its memory bandwidth for streaming tasks. Its maximum memory-read bandwidth is 768 bits per clock. only 60% of its peak bit-crunching performance. DRAM bandwidth is even more limiting. And this is a single core of at least 12 (and at most 64).
This also leaves more power & thermal allowance for the IO Hub on the CPU chip and I guess the CPU is cheaper too.
If your workload is mostly about DMAing large chunks of data around between devices and you still want to examine the chunk/packet headers (but not touch all payload) on the CPU, this could be a good choice. You should have the full PCIe/DRAM bandwidth if all CCDs are active.
Edit: Worth noting that a DMA between PCIe and RAM still goes through the IO Hub (Uncore on Intel) inside the CPU.
It is interesting that despite this we still have programming languages and libraries that cannot exploit pipelining to actually demonstrate IO is the bottleneck and not CPU
I suppose that in real life such ideal condition do not occur, but it shows how badly the CPU is limited by its memory bandwidth for streaming tasks. Its maximum memory-read bandwidth is 768 bits per clock. only 60% of its peak bit-crunching performance. DRAM bandwidth is even more limiting. And this is a single core of at least 12 (and at most 64).