Happened to a client, sent in a 7940x to delid, popped the top to reveal this 3rd party amazon CPU was delidded already and the die was too small to be a 7940x, at best a 7900x.
Moral of the story, do not buy from open box Amazon CPU's. What seemed to happen was the 3rd party seller purchased from Amazon a bulk amount of returned items and he was reselling them, he had no idea and probably was the looser in this case as he took the CPU back.