Dell PowerEdge R720 and R720xd Owner's Manual

Memory bus operating frequency can be 1866 MT/s, 1600 MT/s, 1333 MT/s, 1066 MT/s, or 800 MT/s depending on:

• DIMM type (UDIMM, RDIMM, or LRDIMM)
  • NOTE: PowerEdge R720xd with 3.5 inch hard-drive configuration does not support LRDIMMs due to thermal limitations.
• DIMM configuration (number of ranks)
• maximum frequency of the DIMMs
• number of DIMMs populated per channel
• DIMM operating voltage
• system profile selected (for example, Performance Optimized, Custom, or Dense Configuration Optimized)
• maximum supported DIMM frequency of the processors

The system contains 24 memory sockets split into two sets of 12 sockets, one set per processor. Each 12-socket set is organized into four channels. In each channel, the release levers of the first socket are marked white, the second socket black, and the third socket green.

Figure 1. Memory socket locations

Memory channels are organized as follows:

Processor 1

channel 0: slots A1, A5, and A9

channel 1: slots A2, A6, and A10

channel 2: slots A3, A7, and A11

channel 3: slots A4, A8, and A12

Processor 2

channel 0: slots B1, B5, and B9

channel 1: slots B2, B6, and B10

channel 2: slots B3, B7, and B11

channel 3: slots B4, B8, and B12

The following table shows the memory populations and operating frequencies for the supported configurations.