[dekhn]

There is plenty of HPC that does not need interconnect. It's false, categorically, to say that HPC requires interconnect of any kind.

An isolated, off-net computer - even a desktop PC- stuffed to the gills with GPUs can do HPC. On the other hand, machines connected with 10gbit might do HPC, but you'll have trouble getting codes to scale in a way that is "high performance", relative to what you can get out of threading on a single machine, or a small number of GPUs.

Very little work truly requires classic supercomputers or MPI- there are very few codes where an important engineering problem must be run on a system with low latency, high bandwidth.