As a systems architecture dilettante I really like the Power architecture. It is old school super computer / mainframe architecture on a chip. Parallel processing architecture that makes cross domain inferences impossible etc etc.

A crazy friend of mine had a workstation with a Power10 main board in it running Redhat Linux. Other than the fact that it used what was essentially a rack server main board so had these 8 fans that blew through the chassis like a 747 on take off it was pretty neat.