I do not envy you if you want to battle against Apple
@anybody else who might be interested
http://en.wikipedia.org/wiki/Magnuson–Moss_Warranty_Act
some clips of note:
• the Magnuson–Moss act was enacted by Congress in response to the widespread misuse by merchants of express warranties and disclaimers
• The Act provides that any warrantor warranting a consumer product to a consumer by means of a written warranty must disclose, fully and conspicuously, in simple and readily understood language
• Under the terms of the Act, ambiguous statements in a warranty are construed
against the drafter of the warranty.
• Likewise, service contracts must fully, clearly, and conspicuously disclose their terms and conditions in simple and readily understood language.
• Warrantors cannot require that only branded parts be used with the product in order to retain the warranty. This is commonly referred to as the "tie-in sales" provisions, and is frequently mentioned in the context of third-party computer parts, such as memory and hard drives.
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I am not a lawyer and try to understand this matter using (my amount of) common sense.
What this above stated legal decision means in my humble opinion is simply that commonly available, easily exchangeable standard parts can be used and mounted by the customer even if bought from another supplier than the manufacturer.
Therefore you can add or exchange RAM in any nMP without voiding the warranty for all other parts, besides the self bought RAM, which will NOT be covered by the computer's manufacturer.
The change of a HD or a SSD Drive applies to standard ones and the nMP has no standard SSD Drive but a very special one with a special connector.
Therefore in the special case of a nMP just RAM is considered user upgradable, not the SSD, and this is common sense.
Any change of SPECIAL and ESSENTIAL parts of a computer as a CPU, has in one way or another evident consequences in the whole computer and could cause for instance over heating or many other problems not possible to assess in advance at the moment of the modification.
To believe that Apple will blindly in any case repair such a modified computer is being over optimistic or if you prefer very naïve.
You may print in a 2 meter long banner all the words of the Magnuson-Moss Warranty Act and come with your not working nMP modified by a third part not agreed by Apple to Apple Service to try to FORCE them to ignore all the possible consequences of that modification which might be in one way or another connected to the problem of the computer and to FORCE them to repair free of charge any not working part of your nMP.
I can only wish you good luck in that task..
Your lawyers will cost you much more than the worth of several nMPs and the result of such a battle, which might take a very long time, is more than uncertain.
If you truly decide to have the CPU of your nMP replaced by a third part non agreed by Apple, you should better study in detail the coverage clauses and exclusions provided by THAT company, instead of pretending that Apple will be successfully forced by you and your view of the rights of the consumer in the USA, to do whatever you want them to do.
This is just an opinion of a non lawyer and relies on (my humble) common sense.
Take it or leave it, as you wish...
I am personally not concerned at all.
I am not in the USA and the coverage of Apple is an international one, which is what I need and can use.