We have a Dell Precision 7920 rack with two CPUs and twelve 8-GB of RAM installed.  So, the current memory size is 96 GB.  I am wondering if it is possible to add twelve 16-GB or even 32-GB of DIMM to increase the total RAM size to 288 or even 480 GB.  I am asking because I am not sure if it is okay to mix DIMM modules of different sizes.

Thanks a lot!