System Upgrade Specifications: Standard Memory : 1GB (2 x 512) Memory Type: DDR2 SDRAM, 667MHz, PC5300 Memory Expansion Slot[s]: Two (2) Maximum Memory Expansion: 6 GB Memory added @ time Two (2) Memory board sizes: 1 GB, 2 GB, 4 GB Upgrade Tips : More memory (RAM) increases overall performance and enables your computer to run more applications at the same time. MacBook has two (2) memory upgrade slots. Machine ships with 1GB (2x512MB) of memory. Main memory of the system can be upgraded to 6Gb.