As an Amazon Associate I earn from qualifying purchases @AMAZON
OWC 16GB Memory Modules for 2009/2010/2011 Mac Pro (2011 variant)
The January, 2012 dual-rank modules run at 1333MHz, and can be expected to perform slightly better than what is shown here.
While few users need more than 32GB memory, some do.
The May 2011 availability of 48GB memory in a 4-memory-slot 2009 or 2010 Mac Pro using 16GB memory modules extends the range of applications, such as working with huge panoramic images.
Users of 12-core Mac Pros have the option of 128GB. For obscure system software reasons, the 4-6/core Mac Pro is limited to 54GB a 3 X 16GB + 1 X 8B modules.
Recommendations for maximum memory
Note that accessing more than 32GB memory requires booting with the 64-bit kernel with Mac OS X 10.6.x Snow Leopard.
6-core Mac pro
Stick with 3 modules, unless the particular application demands more, as proven by observation of actual memory use.
48GB as 3 X 16GB (OK to add one 8GB module)
12-core Mac Pro
The January 2012 dual-rank 16GB modules work fine as 8 X 16GB = 128GB in an 8-core or 12-cor Mac Pro.
Continue reading on the next page.