Memory Configurations; Memory Speed; Table 8. Dimms Supported - Dell PowerEdge R720 Technical Manual

Table 8 lists the DIMMs supported on the R720 and R720xd. For the latest information on supported
memory, visit the PowerEdge memory page on
Onl
Capacity
(GB)
4
4
4
8
8
16
16
32
32
32

Memory configurations

The R720 and R720xd servers support flexible memory configurations ranging from capacities of
4GB (minimum) to 32GB (maximum). The R720 and R720xd support up to 12 DIMMs per processor
(up to 24 DIMMs in a dual-processor configuration). Each server has four memory channels per
processor, with each channel supporting up to three DIMMs.
Both systems support 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: UDIMM, RDIMM or LRDIMM. These
types cannot be mixed.
The following additional memory-population guidelines apply to the R720 and R720xd:

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
R720xd Owner's Manual

Memory speed

The R720 and R720xd support memory speeds of up to 1866MT/s, depending on DIMM types
installed and configuration. The loading within a channel significantly affects memory speed.
PowerEdge R720 and R720xd Technical Guide
25
Table 8.
Speed
Type
(MT/s)
1866 RDIMM
1600 RDIMM
1600 UDIMM
1866 RDIMM
1600 RDIMM
1866 RDIMM
1600 RDIMM
1866 LRDIMM
1600 LRDIMM
1333 RDIMM
on Dell.com/Support/Manuals.
Dell.com.
DIMMs supported
Ranks
Data
per SDDC support
width
DIMM
1 X8 Advanced ECC
1 x8 Advanced ECC
1 X8 Advanced ECC
1 x4 All modes
1 x4 All modes
2 x4 All modes
2 x4 All modes
4 x4 All modes
4 x4 All modes
4 x4 All modes
Voltage
1.5
1.35
1.35
1.5
1.35
1.5
1.35
1.5
1.35
1.35
Dell PowerEdge R720 and