How do you upgrade the RAM in the "Unibody" 13-Inch MacBook? How much RAM of what type do they support?

Please note that the "Unibody/Late 2008" 13-Inch MacBook was discontinued and replaced by similar looking "Unibody" 13-Inch MacBook Pro models. Refer to the "Unibody" MacBook Pro Q&A for answers on the "Pro" models.

Upgrading the memory in the "Unibody" 13-Inch MacBook models -- the MacBook "Core 2 Duo" 2.0 13" (Unibody) and "Core 2 Duo" 2.4 13" (Unibody) -- is not quite as simple as it is in the earlier MacBook models, but it still is easy.

The Apple Support Site has posted a detailed article on "How to Install Memory" in the "Unibody" MacBook that provides most of what you need to upgrade the stock memory.

This support document starts by noting that the "Unibody" MacBook models:

Have two memory slots that you access by removing the access door, battery, and bottom case. Your MacBook comes with at least 2 GB (1 GB in each slot) of 1066 MHz Double Date Rate (DDR3) Synchronous Dynamic Random-Access Memory (SDRAM) installed.

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 (3.18 cm)
• 1 Gigabyte (GB) or 2 Gigabyte (GB)
• 204-pin
• PC3-8500 DDR3 1066 MHz Type RAM

Officially, Apple only supports 4 GB of RAM in the "Unibody" MacBook models. Initial tests at the time these models shipped from site sponsor Other World Computing and the always excellent BareFeats demonstrated that they were capable of stably supporting 6 GB of RAM with one 2 GB module and one 4 GB module. It was possible to install 8 GB of RAM as well, but the system was not stable and it was not recommended to install 8 GB of RAM.

However, some time after OWC and BareFeats published their findings, other third-parties reported that these models are capable of stably supporting 8 GB of RAM. In detailed follow up testing, OWC was able to confirm that the "Unibody" MacBook models are capable of supporting 8 GB of RAM, but if -- and only if -- they have been upgraded to run Mac OS X 10.6 "Snow Leopard" or higher and have Boot ROM Version MB51.007D.B03. Note that you may be required to manually update the firmware for the update to work properly. Earlier versions of the operating system (OWC tested running Mac OS X 10.6.6) and earlier Boot ROM versions are not supported.

The Apple document goes 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:

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