Apple Intel-based iMac (Mid 2007) - Manual (Page 32)

32 Chapter 3 Boost Your Memory
Your iMac comes with at least 1 gigabyte (GB) of Double Data Rate 2 (DDR2)
Synchronous Dynamic Random Access (SDRAM) memory installed. You can add 1 GB
or 2 GB memory modules for a maximum of 4 GB of memory. Memory modules must
meet the following specifications:
 Small Outline Dual Inline Memory Module (SO-DIMM) format
 667 MHz, PC2-5300, DDR2 compliant (also referred to as DDR2 667)
 Unbuffered and unregistered
WARNING: Apple recommends that you have an Apple-certified technician install
memory. Consult the service and support information that came with your iMac for
information about how to contact Apple for service. If you attempt to install memory
and damage your equipment, that damage isn’t covered by the limited warranty on
your iMac.