Right. Seymour Cray said that the two big problems in supercomputing were "the thickness of the mat" (of wires on the backplane) and getting rid of the heat.
I wonder if any of his machines ever caught fire, causing an localized out-of-season aurora borealis. On the other hand, Cray machines are never mentioned in the "Halt and Catch Fire" machine code instruction humor.
This is a Cray-I backplane.[1]
[1] https://www.flickr.com/photos/geekmuseum/2926520634/