iMac: Memory specifications and upgrades

Summary

Learn about the types of random access memory (RAM) and video memory (VRAM) used in iMac computers. For specific instructions on installing memory, refer to the linked documents.

iMac Model	Max. DRAM	User Installable Slot	AASP Installable Slot	Video/ VRAM	Notes
iMac (Late 2009)	16 GB	PC3-8500 (1066) DDR3 204-pin SO-DIMM		256 up to 512 MB GDDR3 SDRAM	6
iMac (Mid 2009)	4 GB	PC3-8500 (1066) DDR3 204-pin SO-DIMM		256 up to 512 MB GDDR3 SDRAM
iMac (Early 2009)	8 GB	PC3-8500 (1066) DDR3 204-pin SO-DIMM		256 up to 512 MB GDDR3 SDRAM
iMac (Early 2008)	4 GB	PC2-6400 (800) DDR2 200-pin SO-DIMM		128 or 256 MB GDDR3 SDRAM
iMac (Mid 2007)	4 GB	PC2-5300 (667) DDR2 200-pin SO-DIMM		128 or 256 MB GDDR3 SDRAM
iMac (Late 2006)	4 GB	PC2-5300 (667) DDR2 200-pin SO-DIMM		128 MB GDDR3 SDRAM	5
iMac (Mid 2006) and iMac (17-inch Late 2006 CD)	2 GB	PC2-5300 (667) DDR2 200-pin SO-DIMM		64 MB GDDR3 SDRAM
iMac (Early 2006)	2 GB	PC2-5300 (667) DDR2 200-pin SO-DIMM		128 MB GDDR3 SDRAM
iMac G5 (iSight)	2.5 GB	PC2-4200 (533) DDR2, 240-pin DIMM		128 MB DDR SDRAM	4
iMac G5 (Ambient Light Sensor)	2 GB	PC3200 (400) unbuffered DDR, 184-pin		128 MB DDR SDRAM	2
iMac G5	2 GB	PC3200 (400) unbuffered DDR, 184-pin		64 MB DDR SDRAM	2
iMac (USB 2.0)	1 GB	PC2700 (333) DDR, 2.5V, 200-pin SO-DIMM	PC2700 (333) DDR, 2.5V, 184-pin DIMM	15-inch iMacs: 32 MB DDR SDRAM	2,3
iMac (USB 2.0)	1 GB	PC2700 (333) DDR, 2.5V, 200-pin SO-DIMM	PC2700 (333) DDR, 2.5V, 184-pin DIMM	17- and 20-inch iMacs: 64 MB DDR SDRAM	2,3
iMac (17-inch 1GHz)	1 GB	PC2100 (266) DDR, 2.5V, 200-pin SO-DIMM	PC2100 (266) DDR, 2.5V, 184-pin DIMM	64 MB DDR SDRAM	2,3
iMac (Flat Panel) and (17-inch Flat Panel)	1 GB	PC133, 3.3V, 144-pin SO-DIMM	PC133, 3.3V, 168-pin DIMM	32 MB DDR SDRAM	2
iMac (Early 2001) and (Summer 2001)	1 GB	PC100 or PC133, 3.3V, 168-pin DIMM		8 MB or 16MB	2
iMac (Summer 2000)	1 GB	PC100, 3.3V, 168-pin DIMM		8 MB	2
iMac (Slot Loading)	512 MB	PC100, 3.3V, 168-pin DIMM		8 MB	2
iMac 333 MHz	256 MB	PC100, 3.3V, 144-pin SO-DIMM	PC100, 3.3V, 144-pin SO-DIMM	6 MB	1
iMac 266 MHz	256 MB	PC100, 3.3V, 144-pin SO-DIMM	PC100, 3.3V, 144-pin SO-DIMM	6 MB	1
iMac 233 MHz, iMac 233MHz/B	128 MB; 256 MB for /B models	PC100, 3.3V, 144-pin SO-DIMM	PC100, 3.3V, 144-pin SO-DIMM	2 MB, upgradeable to 6 MB	1

Notes:

All iMac models have two memory slots. Except where stated otherwise, the maximum for each slot is half the total maximum. For example, a computer with a 1GB maximum can take a 512MB module in each slot.
Video memory is only upgradeable in the iMac 233 MHz. Other models are not upgradeable.

The AASP Installable slot can accommodate a 1.5-inch SO-DIMM. The User Installable slot can accommodate a 2.0-inch SO-DIMM.
This computer uses an AGP port. The graphics IC uses a graphics address remapping table (GART) to translate AGP logical addresses into physical addresses. The graphics driver software can allocate memory in both the dedicated SDRAM and the main memory.
Purchase low-profile SO-DIMMs when purchasing larger 256 MB or 512 MB DIMMs for the User Installable slot.
The iMac G5 (iSight) has only one upgradeable memory slot, which can take up to a 2 GB module. The other slot contains a 512 MB module.
Although the iMac (Late 2006) computers will accept up to a 2 GB SO-DIMM in each of the two memory slots, the iMac will only support 3 GB total memory.
The iMac (Late 2009) has four SDRAM slots, each of which can accept a 2 GB or 4 GB SO-DIMM.