All x86 motherboards are in some way Intel reference motherboards -- otherwise they wouldn't be compatible.
Apple designs their own Intel-based motherboards (based on Intel standards as all do), their ARM motherboards completely, and even designs their own ARM chips (based on an ARM core standard, as all do). The Chinese/Taiwanese just produce to Apple's specs, and they often have to re-do their manufacturing in order to be able to handle Apple's specs.
In fact, news came out that Apple has a habit of heavily investing in Chinese factories, building them out, modernizing, making them capable of producing Apple products. Then Apple gets exclusivity and a cut rate on the initial couple years' run.
Where is this done? Cupertino? Massachusetts? The moon? Who runs that division? Do you have some links and references. Apple -Glueing an SSD or memory to a motherboard doesn't count as a big deal in motherboard design. Apple also alters mobo dimensions to fit in its machines. I'm saying the move to Intel chips had many reasons and one is that Quanta is more comfortable w Intel and that Apple takes an Intel reference board and works with Intel and Taiwanese to do does minor tweaking to it. Or tells Quanta or other Taiwanese to tweak it
The Chinese/Taiwanese just produce to Apple's specs, and they often have to re-do their manufacturing in order to be able to handle Apple's specs.
That is way off. Proper phraseology is --- Apple collaborates with Taiwanese to come up w design specs then the Taiwanese/Chinese produce it