I don’t know how good yields are on 14 nm. I know that they will have some salvage, but it is unclear whether that will be sufficient for supplying the whole ThreadRipper market. Salvage (binning by functionality, really) is already part of the cost equation. There is no “free” die. They should be able to sell almost all of the cpu die that they make since they have parts that may only have 2 cores active on the whole chip. They will have some parts that have a whole CCX disabled. That is good since yields on 7 nm probably aren’t great and wafers are significantly more expensive. Are the 6 core cpu die “free” just because they aren’t fully functional?
Binning for functionality with the Epyc IO die isn’t as easy as it is with the cpus. With the cpus, they can disable just about any core. With the IO die, it has external connections such that it probably has to be specific bits that are functional; it can’t just be half overall. The ThreadRipper market is a small enough volume that it may be possible that all ThreadRipper IO die have some defect that prevents them from being an Epyc part. I have heard of cases where manufactures end up selling full functional parts in lower functional bins since there aren’t enough available to fill demand. They can control the demand by manipulating the price though. A fully functional die is a lot more valuable as Epyc than as ThreadRipper, so it yields are good and Epyc demand is high, then expect higher ThreadRipper prices. Even without the cost of an Epyc IO die wafer figures in, I expect the prices for this generation to go up a bit. With 16-core moving down to AM4 at $749, ThreadRipper needs to move up a bit in market placement.
Personally, I would like to see AMD make a bigger push into the workstation market with an actual pro version of ThreadRipper. That would be higher volume such that it would make more sense to develop a cheaper solution for the ThreadRipper class part.