After the very successful Cray-1 and the shelf warmer Cray-2, the new Cray-3 was intended to be another cornerstone in supercomputing, developed once again by Seymour Cray. There was sold only one unit, though, and rumours are, that it wasn't even payed because of stability problems right from the beginning. Cray himself already worked on a Cray-4, which wasn't finished because of the sudden death of S. Cray. The talk spans the last ca. 10 years of Seymour Cray, when he was working on the Cray-3 and Cray-4 supers. It's the last part of a five parts sequel about life and work of Seymour Cray.