For once, there will be a demilitarized zone in the war among major chip architectures Intel x86, ARM, and IBM Power9, which will all be used in a supercomputer being built in Barcelona.
The MareNostrum 4 is being built by the Barcelona Supercomputing Center, and will have three clusters, each of which will house Intel x86, ARM, and Power9 chips. Those clusters will be linked to form a supercomputer that will deliver up to 13.7 petaflops of performance.
All three architectures have never been implemented together in a supercomputer, let alone PCs or servers. That fact raises questions on how the architectures will interoperate.