A few times I get things that are not processors but are memorabilia and are pretty special nonetheless. Today these nice IBM pendants came in. They are very small, measuring barely 37mm square but they weigh an impressive 60 grams. They are a near perfect miniature version of a not so miniature IBM TCM (Thermal conduction module). The 3081 TCM contained the cooling, and a very large MCM used in the 308x mainframe series (made from 1980-1987). Each MCM contained up to 133 dies on a very large ceramic substrate with up to 16,000 contacts for the dies. They were capable of speeds of up to 38MHz. Each TCM was liquid cooled and dissipated around 300 watts of heat. A typical 308x system had 2 dozen of these.
A similar IBM MCM can be seen here: (a 9121 processor)