|  | 
         
          | Option # | Top Level Part #
 | Manufacturing Part #
 | Option Description | Previous Part #
 | Substitute Part #
 |   
          | X7051A | 595-5727 | 501-5030 [F] (512MB) | 2 GB (4 × 512MB SDRAM DIMMs) | 540-5085 | n/a |   
          | X7052A | 595-5728 | 501-5031 [F] (1GB) | 4 GB (4 × 1GB SDRAM DIMMs) | n/a | 501-6173 [F] |   
          | X7053A | 595-5729 | 501-5401 [F] (256MB) | 1 GB (4 × 256MB SDRAM DIMMs) | 540-5084 | n/a |   
          | X7050A [S] | 595-5523 | 501-4489 [F] (128MB) | 512MB (4 × 128MB SDRAM DIMMs) | n/a | n/a |  
 
      
        | Table Legend |  
        | [F] = Field Replaceable Unit (FRU) [S] = Supported, but can no longer be ordered 
                                     with this system
 [N] = No longer supported for this system
 |  |