Early 2009 - MacPro4,1
Compatible upgrades for Early 2009 Mac Pro's.
Specifications for: "Quad Core" 2.66, "Quad Core" 2.93, "Quad Core" 3.33
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.
RAM Slots: 4
Specifications for: "Eight Core" 2.26, "Eight Core" 2.66, "Eight Core" 2.93
Standard RAM: 6 GB
Maximum RAM: 128 GB*
Details: By default, 6 GB of RAM was installed as six 1 GB modules. Two slots free.
*Apple officially supports 32 GB of RAM in this model, but as first discovered that it is capable of using 64 GB of RAM when booting MacOS X 10.6 "Snow Leopard" in 64-bit mode. Later, this unofficial maximum RAM bumped to 96 GB running Mac OS X 10.6 or 10.7, and yet again 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.
RAM Slots: 8*