It was "Skylake's poor quality assurance" that ultimately led to Apple's decision to abandon Intel and focus on its own ARM-based processors for high-performance machines. This is the assertion of François Piednoele, an outspoken former Intel representative engineer.

This was one of the big stories of the past week. Apple finally announced a two-year transition from Intel for its Mac desktop and notebook lines. There is a lot of speculation as to why this has happened, but the main thought is that they are aiming to integrate their architecture across all their different platforms, from the iPhone, through the iPad, and eventually to laptops and desktops.

While it makes perfect sense from a business and architecture perspective, Piednoël says it is something that was always considered by Apple, but had the company not found so many problems within the Skylake architecture, it would still be on the Intel would have been on the chip train, he believes. It was the straw that broke Apple's back, so to speak.

"Skylake's QA was more than problematic," Piednoele says in a casual Xplane chat and stream session. It was unusually bad; even the most trivial things were over-remarked upon inside Skylake." Basically, our friends at Apple became the first to discover the problems in this architecture. And it went really, really badly

"If your customers start finding bugs as bad as you found them, you're not leading them to the right place."

If that's true, it would explain why polo-shirted Apple officials might have started thinking pretty seriously about how to effectively switch both their engineering and manufacturing to ARM, and the entire Mac software ecosystem to ARM. Apple must have really hated Skylake...

However, at the recent VLSI Technology and Circuits conference, Intel CTO Mike Mayberry separately pointed out that QA is a matter of scale. Enterprises and exascale customers will be dealing with far more chips than a company like Intel can check in-house. And in that case, no matter which silicon Intel, AMD, or ARM checks, it is not unlikely that the customer will find a bug.

But I don't know if that is a recent phenomenon. Certainly at the time, Pied-Noel seemed convinced that it was an unusual situation.

"For me, this is the inflection point," says Piednoel. 'The guys at Apple, who were always thinking about switching, actually considered switching and said, "Well, we're not going to do this."' Basically, it was the poor quality assurance of Skylake that caused them to actually leave the platform."

This is still only the professed opinion of one former Intel engineer and cannot necessarily be taken as pure fact, nor is it clearly the only reason Apple switched. However, Pied-Noel was always an interesting and very outspoken person during his time at Intel.

But whether or not the quality assurance of the Skylake architecture influenced Apple's decision to switch entirely to ARM, it is interesting to get a perspective from someone inside Intel at the time as to why it ultimately happened.