Late 2009 - iMac11,1
compatible for 27inch 2.66Ghz and 2.8Ghz - MB953LL/A, MC507LL/A
Standard RAM: 4 GB
Maximum RAM: 32 GB*
Details: By default, 4 GB of RAM was installed as two 2 GB SO-DIMM modules. Two slots free.
RAM Slots: 4
*Officially, this model supports a maximum of 16 GB of RAM. However, this model can support up to 32 GB of RAM if it is running Mac OS X 10.6.3 "Snow Leopard" or higher in 64-bit mode and has been updated to use the latest EFI version. It is limited to 16 GB of RAM in 32-bit mode.