Hello arabid, Yes you can have 64GB of memory in your MX3230.  The NX3230 uses a PER730xd chassis.  So when looking to upgrade you would compare the specs of a PER730xd.  Please let us know if you have any other questions.
Hi, Dell Storage NX3230 NAS comes with maximum 32GB RAM, Can anyone please confirm that I can add more RAM by myself to get total 64GB Memory? And why we cannot order NX3230 with more than 32GB RAM? Regards,Abdul Rehman Abid  
Dell NX3230 NAS Memory Upgrade