Using a 128GB MicroSD card with a device with 64GB maximum? Samsung's specs for my Galaxy S3 say:



128GB MicroSD cards probably didn't exist when this phone was made.

If I insert a 128GB MicroSD card, will the card:


"not function at all" 


or will it:


"work fine" but only let me use 64GB?
It will work fine and you'll have access to the entire storage space. 



It's usually just a recommendation for a better user experience in my opinion, If I used the recommended maximum SD Card size on my device It'd be able to load all my photos, music, app data  without any serious delay, however if I put a huge SD Card in my device it could take hours to load 128gb worth of photos, Therefore it's necessary to recommended a maximum size for the best user experience.   

You will need to format your SD Card to Fat32 on a PC if it's not already formatted.   

A good free software for this on Windows would be   



Aomi Partition Assistant