||18 (9 slots per CPU)
||Systems feature 1 or 2 processors each controlling 3 memory "channels" of 3 DIMM slots each. For best performance balance the total memory capacity equally between both CPUs. Overall memory speed is dependent upon the processor model and memory configuration. 1 or 2 single- or dual-rank DIMMs per channel enables memory speed of up to 1333MHz; 3 DIMMs per channel reduces speed to 800MHz for single or dual-rank DIMMs; maximum speed with quad-rank DIMMs is 1066MHz with 1 DIMM per channel and 800MHz with 2 DIMMs per channel; 3 quad-rank DIMMs are not supported.