AMD Ryzen lineup to be crippled by 14nm yield issues?

In our previous post I discussed the Core i7 7740K and Core i5 7640K rumors from CanardPC. Word on the street is that the performance of AMD's Ryzen surprised Intel and that the chip giant is making last-minute damage control changes to its lineup. For consumers this is good news as we can expect more performance for less money.

Why are the quad-cores engineering samples so slow?
The French site also has some fresh rumors about Ryzen which deserved a separate post. If this rumor is true, it seems AMD is once again struggling with process issues. Ryzen quad-core processors reportedly need to hit a frequency of 3.8GHz to 4.2GHz to compete with Intel's lineup but current engineering samples are doing just 3.2GHz. This is pretty weird considering there are eight-core models making the rounds that hit 3.4GHz/3.8GHz and 3.6GHz/4.0GHz.

CanardPC notes it has access to engineering samples of six-core and eight-core versions of Ryzen with B stepping but writes that it does not know the Turbo frequencies of the quad-core B-stepping samples. The site does know that between stepping A0 and B, the Turbo mode of the eight-core models increased by 400MHz. The A0 stepping of the quad-core Ryzen was capable of hitting 2.9GHz base and 3.4GHz Turbo, so if we can draw a parallel here the B stepping may achieve a Turbo of 3.8GHz, which seems too little to compete with the Intel Core i5 7640K.

Yield problems once more?
The first eight-core processors have higher frequencies thus the reporter thinks the GlobalFoundries 14nm process is suffering from yield issues. Basically the eternal Achilles heel of AMD.

CanardPC claims all initial six-core and quad-core Ryzen processors will be based on defective eight-core models. Basically, AMD will only make eight-core Ryzen parts and processors with defective cores or chips that are unstable at higher frequencies will be recycled as lower-clocked quad-core and six-core models.

If this rumor is correct, AMD will have high-performance eight-core chips with a big "wow" factor but these chips will likely be quite expensive. Until the GlobalFoundries yield issues are solved or until AMD can secure 14nm Ryzen supply from Samsung, the rest of the Ryzen lineup may be severely crippled. The company will do its best to recycle as many defective dies as possible but this will put constraints on availability and may lead to higher prices than expected.

We will know soon enough if the launch lineup does not include competitive quad-core parts.