1. A method of replacing a memory module in a computer system comprising a plurality of memory cartridges each of the plurality of memory cartridges receiving power comprising the acts of: (a) detecting a fault in one of the plurality of memory cartridges; (b) powering-down only the one of the plurality of memory cartridges in which a fault was detected; (c) removing a memory module from the powered-down memory cartridge; (d) inserting a replacement memory module into the powered-down memory cartridge; and (e) powering-up the one of the plurality of memory cartridges.