Dell PowerEdge M820 Technical Guide - Page 18

Table 7 lists the DIMMs that are supported on the M820. For the latest information on supported memory, visit Dell.com. Only Capacity Speed (GB) (MT/s) Type Ranks per DIMM Data width SDDC support Voltage 2 1600 RDIMM 1 x8 Advanced ECC 1.5 2 1333 RDIMM 1 x8 Advanced ECC 1.35 2 1333 RDIMM 1 x8 Advanced ECC 1.35 4 1333 RDIMM 2 x8 Advanced ECC 1.35 4 1600 RDIMM 2 x8 Advanced ECC 1.5 4 1333 RDIMM 1 x4 All modes 1.35 4 1333 RDIMM 2 x8 Advanced ECC 1.35 8 1333 RDIMM 2 x4 All modes 1.35 8 1333 RDIMM 2 x4 All modes 1.35 8 1600 RDIMM 2 x4 All modes 1.5 16 1066 RDIMM 4 x4 All modes 1.35 16 1600 RDIMM 2 x4 All modes 1.5 16 1333 RDIMM 2 x4 All modes 1.35 32 1333 LRDIMM 4 x4 All modes 1.35 32 1333 RDIMM 4 x4 All modes 1.35 Flexible memory configurations are supported on the M820, ranging from capacities of 2GB to 1.5TB. The M820 supports up to 12 DIMMs per processor (up to 48 DIMMs in a four-processor configuration). Each processor has 4 memory channels, with each channel supporting up to 3 DIMMs. The M820 supports a flexible memory configuration, according to the following basic rules:  Speed: If DIMMs of different speeds are mixed, all channels across all processors operate at the slowest DIMM's common frequency.  DIMM type: Only one type of DIMM is allowed per system: RDIMM or LRDIMM. These types cannot be mixed. The following additional memory population guidelines apply to the M820:  Up to two quad-rank (QR) DIMMs and up to three dual-rank (DR) or single-rank (SR) DIMMs may be populated per channel. Although an LRDIMM is physically a QR DIMM, logic on the LRDIMM can make it appear as a DR DIMM to the system, allowing up to three LDRIMMs per channel.  DIMMs must be installed in each channel, starting with the DIMM farthest from the processor.  DIMMs should be installed with largest rank count to smallest. For example, if DR DIMMS are mixed with SR DIMMs, DR DIMMS should be placed in the lowest DIMM slots, followed by the SR DIMMs. For more information on memory configuration and population, see the Dell PowerEdge M820 Systems Owner's Manual on Support.Dell.com/Manuals. 18 PowerEdge M820 Technical Guide