In response to the hoopla surrounding Threaderipper and its four dies, two of which are non-functional, or "dummy dies" as AMD calls them, an AMD exec took to Twitter to clarify things. According to James Prior, AMD's Senior Product Manager, the two so-called dummy dies are "basically rocks" and cannot be enabled.
The confusion over Threadripper started when renowned overclocker der8auer delidded a Threadripper processor last month and discovered four dies, just like AMD's server-based Epyc chips. AMD asked him to remove the video from YouTube, and then explained to him and the rest of the world that two of the dies on Threaderipper are dummy dies included for structural stability.
That would have been the end of it, except that der8auer last week picked up a retail Threadripper 1950X processor and again gave it the delidding treatment. He also cleaned up the dies and discovered that even the non-functioning ones contained integrated circuits and transistors. This suggested that AMD wasn't being entirely truthful about the use of dummy dies, and some speculated that it might somehow be possible to enable the two non-functioning dies.
Threadripper is not a Epyc processor. Different substrate, different dies. 2 dies work, other 2 have no path to operation. Basically rocks.September 17, 2017
Well, that is not the case. While everyone can argue the semantics of what constitutes a dummy die, the bottom line is that Threadripper is not an Epyc chip. According to Prior, Threadripper uses a different substrate, and that the non-functioning dies "have no path to operation."
In other words, Threadripper and Epyc use the same base manufacturing to reduce costs, but half of the Threadripper dies are predetermined to be dead. AMD is choosing to refer to them as dummy dies instead of inactive because the latter implies they could be activated.
Yes, exactly why they're not described as inactive, but dummy. Doesn't matter if they were dead, or active, they're not going to work.September 17, 2017
So there you have it. Threadripper is using actual dies as opposed to blank slabs, but there is no way to utilize them (even if they're not defective).