Is the 2 GB maximum RAM capacity for the MacBook Pro "Core Duo" a true limit? Would it support 4 GB of RAM if I installed dual 2 GB SO-DIMMs?

Please note that the MacBook Pro "Core Duo" series was discontinued on October 24, 2006. It was replaced by the "Late 2006" MacBook Pro "Core 2 Duo" series.

As noted on the MacBook Pro specs pages and elsewhere in the MacBook Pro Q&A on EveryMac.com, Apple supports installing a 1 GB PC2-5300 (667 MHz) DDR2 SO-DIMM in each of two RAM slots for a maximum of 2 GB of RAM in the MacBook Pro "Core Duo" models.

The User's Guide further elaborates that both memory slots can accept an SDRAM module that meets the following specifications:

• Double Data Rate Small Outline Dual Inline Memory Module (DDR SO-DIMM) format
• 1.25 inch or smaller
• 512 MB or 1 gigabyte (GB)
• 200-pin
• PC2-5300 DDR2 667 MHz Type RAM

In terms of "official" answers, that's it. The MacBook Pro "Core Duo" does not support more than 2 GB of total RAM.

However, Apple generally provides the official "maximum RAM" based on the highest capacity memory modules available at the time the system is shipped. Some systems later can be upgraded beyond this amount when higher-capacity modules become available. On the other hand, some other systems cannot be upgraded beyond the maximum originally stated by Apple.

On July 13, 2006, APC Magazine reported that:

“It seems that it is not possible,” said Transcend [a memory manufacturer] spokesperson Marielle Bonne, speaking to APC from Taiwan after the company mistakenly issued a press release saying the RAM would work in Apple’s Intel-based notebooks.

“After checking, here is the information I got from our tech support: Apple MacBook and MacBook Pro (both with Intel Core) can only support 2 GB memory max (1 GB memory for each slot, total 2 slots available).

“Therefore it’s not possible to put 2 x 2 GB for a total memory capacity of 4 GB in Apple MacBook Pro or MacBook.”

This is no doubt a disappointment to those interested in installing more than the officially supported 2 GB of total RAM in the MacBook Pro "Core Duo".