Systems feature 1 or 2 processors each controlling 3 memory "channels" of 2 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 DIMM per channel enables memory speed of 1333MHz; 2 DIMMs per channel reduces speed to 1066MHz; maximum speed with quad-rank DIMMs is 1066MHz with 1 DIMM per channel and 800MHz with 2 DIMMs per channel.