How do you upgrade the RAM in the "Mid-2010" Mac Pro models? How much RAM of what type do these models support?

Just as it is for all earlier Mac Pro models, upgrading the memory in the "Mid-2010" Mac Pro is quite simple.

However, it is critical that memory meet precise standards to function properly. In the PDF instruction manual, Apple specifies that all UDIMMs must meet these specifications:

• PC3-10600E, 1333 MHz, DDR3 SDRAM UDIMMs
• Error-correcting code (ECC)
• 72-bit wide, 240-pin ECC modules
• 36 ICs maximum per ECC UDIMM

Apple also notes that "although the memory speed of the UDIMMS is 1333 MHz, they will operate at 1066 MHz or 1333 MHz depending on the processor in the computer."

This is interesting as the entry-level Mac Pro "Quad Core" 2.8 (2010/Nehalem) configured with its stock 2.8 GHz Xeon W3530 processor or upgraded via build-to-order with a 3.2 GHz Quad Core "Nehalem" Xeon W3565 processor as well as the standard high-end Mac Pro "Eight Core" 2.4 (2010/Westmere) both work with 1066 MHz DDR3 ECC SDRAM (PC3-8500) modules and there is no advantage to installing faster memory. Other models -- those configured with a "Westmere" processor with the exception of the standard Mac Pro "Eight Core" 2.4 (2010/Westmere) -- are intended to use 1333 MHz DDR3 ECC SDRAM" (PC3-10600) modules.

Even more interestingly, in real-world testing, the respected MacPerformanceGuide actually found no difference in real-world performance in a system intended to use 1333 MHz PC3-10600 modules even if the slower 1066 MHz PC3-8500 modules were installed.

Nevertheless, Apple presumably is erring on the side of caution as 1333 MHz memory are designed to work in models that support the slower 1066 MHz memory, but not vice versa. The company formally states that "DIMMs from older Mac computers can not be used in your [Mid-2010] Mac Pro." The company also specifies:

When purchasing DIMMs for use in Mac computers, make sure that the memory vendor conforms to the Joint Electron Device Engineering Council (JEDEC) specification. Check with your memory vendor to ensure that the DIMMs support the correct timing modes and that the Serial Presence Detect (SPD) feature has been programmed properly, as described in the JEDEC specification.

In other words, a "Mid-2010" Mac Pro, and Macs in general, can be picky about memory and it is important to purchase from a vendor that has tested their memory in a particular Mac model to ensure compatibility.

Although "Mid-2010" models with a single processor officially support a maximum of 16 GB of RAM, as discovered by site sponsor Other World Computing, they actually can support more. OWC first noted an actual maximum of 32 GB of RAM and later increased this actual maximum to 48 GB of RAM.

Models with dual processors likewise officially support 32 GB of RAM, but again, OWC found they actually can support more. OWC first confirmed an actual maximum of 64 GB of RAM running Mac OS X 10.5 "Leopard" and later increased this maximum to 96 GB of RAM running Mac OS X 10.6 "Snow Leopard" or 10.7 "Lion." More recently, OWC yet again discovered these dual processor models can support up to 128 GB, but only when running a 64-bit version of Windows XP or later or Linux. Mac OS X only can support 96 GB of RAM.

Apple covers installing memory in the "Mid-2010" Mac Pro models on pages 43-60 of the PDF User's Guide -- complete with drawings -- and this absolutely should be read before upgrading the memory. Just as it is for the "Early 2009" models, note that installing RAM in groups of three will provide maximum performance.

Perhaps even better than the official drawings, however, OWC provides a step-by-step video of the upgrade process:

In addition to providing helpful installation videos, Other World Computing also has quality memory that is guaranteed to work with the "Mid-2010" Mac Pro line at an affordable price.