How do you upgrade the RAM in the "Aluminum" iMac Core 2 Duo models? How much RAM of what type do these systems support?

Unlike their predecessors, all of the "Aluminum" iMac Core 2 Duo systems -- both the "original/Mid-2007" and "Early 2008/Penryn" models -- support the same maximum memory capacity (4 GB). Upgrading the RAM in all of these systems is easy, but the "original/Mid-2007" and "Early 2008/Penryn" models use different types of memory.

The Apple Support Site provides helpful documents about "Installing or Replacing Memory" for the "original/Mid-2007" and "Early 2008/Penryn" iMac models, respectively. Both documents note that all "Aluminum" Intel-based iMac models have "two side-by-side Synchronous Dynamic Random-Access Memory (SDRAM) slots in the bottom of the computer, and come with at least 1 GB Double Data Rate (DDR2) SDRAM installed into one slot."

The "original/Mid-2007" Aluminum models -- the iMac "Core 2 Duo" 2.0 20-Inch (Al), "Core 2 Duo" 2.4 20-Inch (Al), "Core 2 Duo" 2.4 24-Inch (Al), and "Core 2 Extreme" 2.8 24-Inch (Al) -- use 667 MHz PC2-5300 DDR2 SDRAM, which Apple further specifies must meet all of the following criteria:

• PC2-5300
• Unbuffered
• Nonparity
• 200-pin
• 667 MHz DDR2 SDRAM

The "Early 2008/Penryn" Aluminum models -- the iMac "Core 2 Duo" 2.4 20-Inch (08), 2.66 20-Inch (08), 2.8 24-Inch (08), and 3.06 24-Inch (08) -- use 800 MHz PC2-6400 DDR2 SDRAM, or specifically:

• PC2-6400
• Unbuffered
• Nonparity
• 200-pin
• 800 MHz
• DDR2
• SDRAM

According to Apple, "DIMMs with the following features are not supported" by either line of iMac models:

• Registers or buffers
• PLLs
• Error-correcting code (ECC)
• Parity
• Extended data out (EDO) RAM

The "Installing and Replacing Memory" documents continue with detailed instructions complete with drawings for replacing the RAM in both the top and bottom slot of these iMacs. By following the instructions closely, you should have the RAM upgraded in no time.

Please note that just because RAM meets the minimum listed criteria does not mean that it will necessarily function as intended in a particular Mac. When buying memory, be sure to buy from a quality vendor that has tested their RAM with your Mac to ensure compatibility.

Site sponsor Other World Computing sells memory guaranteed to be compatible with all of the Intel-based iMac models.

Also see: How do you upgrade the RAM in the White iMac "Core Duo" and "Core 2 Duo" models? How much RAM of what type do these systems support?