I accidentally installed 4 x 8 Gb RAM into my quad core early 2009 Mac Pro. It supposedly maxes out at 4 x 4 Gb of RAM. The computer does recognize that 32 Gb of total RAM is installed. My question is: "Will the computer utilize only 16 of the 32 Gb of RAM installed? Will it make it less efficient than if I had installed 4x 4Gb of RAM instead?"
You are fine, and actually could go larger if needed.
The official Apple limitation of 4 by 4GB of RAM was released before larger DIMMs were available. by the time larger DIMMS were widely available, that model was discontinued.
Everymac.com has this to say about RAM expansion on that model:
Standard RAM: 3 GB. Maximum RAM: 48 GB*
Details: By default, 3 GB of RAM was installed as three 1 GB modules. One slot free.
*As originally shipped, Apple officially supported a maximum of 8 GB of RAM but third-parties discovered that the system could actually support 16 GB of RAM using four 4 GB memory modules. On December 4, 2009, Apple "officially" began supporting 16 GB of RAM as well. Shortly thereafter, third-parties determined that the system could, in fact, support 32 GB of RAM using four 8 GB modules. Finally, third-parties have been able to support 48 GB of RAM with three 16 GB modules.
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16GB DIMMs are "Registered" DIMMs, and can NOT be mixed with ANY smaller sizes.
You are fine, and actually could go larger if needed.
The official Apple limitation of 4 by 4GB of RAM was released before larger DIMMs were available. by the time larger DIMMS were widely available, that model was discontinued.
Everymac.com has this to say about RAM expansion on that model:
Standard RAM: 3 GB. Maximum RAM: 48 GB*
Details: By default, 3 GB of RAM was installed as three 1 GB modules. One slot free.
*As originally shipped, Apple officially supported a maximum of 8 GB of RAM but third-parties discovered that the system could actually support 16 GB of RAM using four 4 GB memory modules. On December 4, 2009, Apple "officially" began supporting 16 GB of RAM as well. Shortly thereafter, third-parties determined that the system could, in fact, support 32 GB of RAM using four 8 GB modules. Finally, third-parties have been able to support 48 GB of RAM with three 16 GB modules.
-----
16GB DIMMs are "Registered" DIMMs, and can NOT be mixed with ANY smaller sizes.
Early 2009 Quad Core Mac Pro
