If a person buys a 2011 iMac with HDD, takes it to an Apple authorized repair shop, and has the HDD replaced by an Apple SSD, will that affect the Applecare warranty? I know a non Apple SSD would probably void the warranty.
I have no direct experience, but everything I've read here from people reporting actual experiences (as opposed to opinions) is that your AppleCare is not voided by adding non-Apple parts either by yourself or through an authorized dealer - as long as the installation itself didn't break anything.
However: If the non-Apple part should break in such a way as to cause other problems then your AppleCare may be void. For example, if a chip on the SSD blows and sparks over to logic board, then you may not be covered.
Also... The new part - even if an Apple part - may not carry the same warranty coverage as original part covered by AppleCare. Whatever warranty the shop quotes you, get it in writing. Also - clarify what happens if the new part fails and takes out the logic board.
Internal upgrades on the iMac are sorta grey area. I think most people would agree, it shouldn't technically void anything. Even if it's a third party SSD.
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I disagree. I don't think it's a grey area at all, at least not from the experiences of people I've read who have made warranty claims.