Taiwanese tech site DigiTimes has good and bad news about AMD's Zen processor. Lets start with the good news, the first engineering samples are expected in the near future as the site remarks that Zen is seeing stable development and has satisfactory yields.
The bad news concerns a rumor about poor USB 3.1 performance with Zen. AMD outsourced the Zen chipset production to ASMedia Technology and sources at motherboard makers claim USB 3.1 bandwidth drops dramatically as circuit distance increases.
A design limitation in the Zen chipset is to blame for this but fortunately it can be resolved with some extra components. However, this is expected to increase the manufacturing cost of a Zen motherboard by $2 to $5:
Because of the Zen chipsets' design limitations, USB 3.1 transmission speeds drop dramatically as circuit distance increases, forcing PC and motherboard players to add additional retimer and redriver chips or even an independent USB 3.1 IC in order for the function to work properly. This has thus increase the makers' costs.
Since PC sales have been weakening and the increased costs are likely to impact motherboard players' demand for the Zen chipsets, AMD is reportedly considering acquiring retimer and redriver chips via third-party suppliers to sell along with the Zen chipsets, but so far the sources have not yet heard any firm details on costs or development.