How do you upgrade the RAM in the "Mid-2009" 13-Inch, 15-Inch, and 17-Inch MacBook Pro Core 2 Duo models? How much RAM of what type do they support?

Upgrading the RAM in the "Mid-2009" 13-Inch, 15-Inch, and 17-Inch MacBook Pro models is fairly easy. It's not quite as easy as it is for the "pre-Unibody" MacBook Pro systems, as the "Mid-2009" line requires a screwdriver, but it still is simple and straightforward.

Apple explains how to install memory (and the hard drive) on pages 35-48 of the 13-Inch, 15-Inch, and 17-Inch "Mid-2009" MacBook Pro User Guides, respectively, and this provides most of what you need to know to upgrade the pre-installed memory.

Apple first notes that the "Mid-2009" MacBook Pro models have:

Two memory slots that you access by removing the bottom case. Your MacBook Pro comes with a minimum of 2 gigabytes (GB) of 1066 MHz Double Data Rate (DDR3) Synchronous Dynamic Random-Access Memory (SDRAM) installed. Each memory slot can accept an SDRAM module that meets the following specifications:

• Double Data Rate Small Outline Dual Inline Memory Module (DDR3) format
• 30 mm (1.18 inches)
• 204-pin
• 1 GB, 2 GB, or 4 GB
• PC3-8500 DDR3 SO-DIMM 1066 MHz Type RAM
  

For models with "integrated graphics" (which have graphics processors that share memory with the system) -- the MacBook Pro "Core 2 Duo" 2.26 13" (SD/FW), "Core 2 Duo" 2.53 13" (SD/FW), and "Core 2 Duo" 2.53 15" (SD) -- Apple recommends that you "fill both memory slots and install an identical memory module in each slot".

However, third-party tests from site sponsor Other World Computing have shown that generally the performance gain from having more memory installed -- 6 GB rather than 4 GB, for example -- more than offsets the loss in graphics performance caused by the "mismatched" configuration even on the systems with "integrated graphics". All of the "Mid-2009" MacBook Pro models officially and unofficially support 8 GB of RAM.

The Apple manuals go on to provide installation instructions complete with drawings, which absolutely should be read in their entirety before one installs memory, but perhaps even better, OWC provides a convenient step-by-step video of the process for the 13-Inch model (and the 15-Inch and 17-Inch model are quite similar):

In addition to instructional videos, as you would expect, Other World Computing offers memory and hard drive upgrades for all MacBook Pro "Unibody" systems.