Don't forget that one of the milestone things in Beowulf cluster was Stone Soup cluster, and the whole Beowulf cluster thing was heavily about "we don't have money for supercomputer, we hacked something from random junk"
My jam was rather Openmosix, but same vibe: throw whatever you have into the cluster and be happy with the inefficiency because those resources would sit unused otherwise !
Early early google seems to have used scavenged machines from university as soon as it outgrew what was essentially a phd project? I recall a photo of random assortment of Sun sparcstations and the like.
