The original "Bondi" iMac, Rev-B iMac, and 5 colored or "flavored" iMacs all share the same logic board, which features two memory expansion slots. These slots accept either 32MB, 64MB, or 128MB SDRAM DIMMS using 64-Mbit technology, or 128MB DIMMs using 128-Mbit technology. All SDRAM DIMMs used in the original iMac family must be 3.3 volt (V), unbuffered, 64-bit wide, 144-pin, with correctly programmed Serial Presence Detect. According to Apple specifications, SDRAM speed must be 100MHz, 10ns or faster (meaning a lower number).
The original M6709LL /A iMac shipped standard with 32MB SDRAM, expandable to 128MB. The /B iMac, the 266MHz, and the 333MHz models, shipped standard with 32MB SDRAM, expandable to 256MB.
Note: Although /A iMac computers may work with higher density SO-DIMM's, such memory was not available at the time of product development, and is therefore not warranted to work correctly by Apple.
The iMac's two memory expansion slots accommodate standard SO-DIMMS. The expansion slot on the underside of the board is normally occupied by the factory-installed SO-DIMM. The top slot is intended for a user-installed SO-DIMM. The lower SDRAM expansion slot will only accommodate SO-DIMMs 1.0-inch to 1.5-inches in height. A 2.0-inch SO-DIMM will not physically fit into the slot, and therefore is neither supported nor endorsed. If a 128MB SO-DIMM is smaller than 1.5 inches, and meets or exceeds remaining specifications criteria discussed on this page, it will likely work in the lower expansion slot.
Note: SDRAM DIMMs can be installed one at time and in any slot, as interleaving is not supported on these machines. If you are attempting to install 128MB SO-DIMMS, ensure they meet or exceed serial presence detect, type, and speed specifications for use in the iMac.
Mixed Memory Types
The iMac computer uses SDRAM SO-DIMMs only. EDO memory will not work in the iMac computer. System problems will result if EDO memory is installed.
Note : When upgrading the memory in iMac computers, it is possible to inadvertently mix EDO and SDRAM memory. If incompatible memory types are installed, the computer will beep several times when the user attempts to restart the computer
Video Memory Notes
The iMac logic board shipped with 2MB Synchronous Graphic RAM (SGRAM) video memory soldered on the logic board. The logic board also contains a video memory expansion slot that accepts a Small Outline DIMM (SO-DIMM) to increase video memory to a maximum of 6MB. Apple supports a 4MB SGRAM SO-DIMM that is 32-bit wide, 144-pin, fast-paged, 83 MHz/12 ns cycle time or faster.
Important: Use only SGRAM SO-DIMMs. Never use the 256K or 512K video memory DIMMs used in older Macintosh computers.
Video Memory Note: The M6709LL/A iMac shipped standard with 2MB SGRAM video memory, upgradeable to 6MB. The /B, the 266MHz, and the 333MHz iMacs, shipped standard with 6MB SGRAM: 2MB on the logic board and a 4MB module pre-installed in the video memory slot. Such configurations are not further upgradable.
|Logic Board RAM||None|
|Supported DIMMs||32MB, 64MB, 128MB (all 64-Mbit), and 128MB (128-Mbit).|
|Number DIMM Slots||Two(2)|
|Supported VRAM||2MB SGRAM soldered on the board(/A iMac), 6MB SGRAM with 4MB installed in the video memory slot(/B iMac, 266MHz, and 333 MHz iMacs)|
|Number VRAM Slots||One|
|L2 Cache Supported?||512K backside level 2 cache on processor module; 133-MHz dedicated 64-bit backside bus|
|DIMM Type||SDRAM, 3.3v, unbuffered, 64-bit wide, 144-pin, with Serial Presence Detect.|