Memory for Sun's M9000 servers is installed on a CPU/Memory Board Unit (CMU), each containing thirty-two DIMM slots and supporting up to 256GB of memory. Sun's M9000 server with 64 processors supports up to sixteen CMU's and maximum 4TB of Dataram memory. DIMMs on the Memory Boards are divided into two groups--A and B. DIMMs in Group A must be the same or larger capacity than the DIMMs in Group B. Group B can have the same number of DIMMs as Group A or it can have zero DIMMs.