Xserve Memory for Model 3,1 (Early 2009)

The Xserve 3,1 DDR3-1066 comes in two versions, the 4-core and the 8-core. The 4-core has 6 DIMM slots, and it is upgradable to a maximum of 24GB with the installation of 6x 4GB modules (2x 12GB kits). The 8-core has 12 slots, and it is upgradable to a maximum of 48GB with the installation of 12x 4GB modules (4x 12GB kits). Since this Xserve runs a "Tri-Channel" memory interface, memory MUST be installed in matched sets of three at a time.

Matched Modules: The Xserve 3,1 Intel DDR3-1066 runs a Tri-Channel memory interface. The Ramjet kits for the Xserve DDR3-1066 contain a matched set (3x) of DIMMs. The kit will consist of identical brand/model/spec IC's. They will be from a single batch, and will have matching series numbers. This ensures maximum performance, and perfect compatibility.

Please view Apple's installation guide for more information.
Apple's installation guide.