It should be noted that most CPUs do use DDR4 for good reason: they have an expectation to use more than the capacity of HBM2. GPUs (and a supercomputer CPU, like the A64FX) can rely upon the fact that their workloads are designed for distributed-compute and/or otherwise fit inside of 32GBs or 40GBs.
CPUs on the other hand, could very well be reading/writing to a 2TB in-memory database these days, even on a single-socket single-node system like AMD EPYC. That flexibility to have as much (or as little) RAM as the customer demands is a major advantage of traditional CPUs like EPYC or Xeon, which the A64FX cannot partake in.
If you need more than 32GBs of RAM, A64Fx is a no-go. That HBM2 is soldered directly onto the package and cannot expand.
Yes, and 32 GB seems rather limited for a 48 core chip.
While not a "general purpose" CPU, this HPC CPU does show IMO that it's at least possible of making a CPU that does compete in some aspects with what GPUs do.
Although an A100 still has twice the bandwidth and over 3x the GFLOPS without tensor cores and more than 6x with.
