Determine Maximum RAM/Memory Capacity In Linux Using dmidecode

dmidecode -t 16

Would yield something like:

# dmidecode 2.11
SMBIOS 2.5 present.

Handle 0x1000, DMI type 16, 15 bytes
Physical Memory Array
        Location: System Board Or Motherboard
        Use: System Memory
        Error Correction Type: Multi-bit ECC
        Maximum Capacity: 65280 MB
        Error Information Handle: Not Provided
        Number Of Devices: 8

So this board has 8 memory banks and can support 64GB of ram