The iMac (Late 2009) computer has four SDRAM slots in the bottom of the computer and comes with at least 4 GB DDR3 SDRAM installed as two 2GB DIMMs into two slots.
The maximum amount of RAM you can install in the computer is 16 GB (a 4 GB SO-DIMM in each slot).
You can use any Small-Outline dual inline memory modules (SO-DIMMS) that meet all of these criteria:
- 1066 MHz
- DDR3 SDRAM
You can use RAM module sizes of 2 GB or 4 GB in each slot.
DIMMs with any of the following features do not work in the iMac (Late 2009):
- Registers or buffers
- EDO RAM
Always follow the upgrade instructions for memory installation as written. Never attempt to remove any screws that are not listed in the upgrade instructions.
For more information about upgrading your iMac (Late 2009) memory, see iMac (Late 2009): Installing or replacing memory.