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PowerEdge 11th Generation Servers: R810, R910, and M910 Memory Guidance
Page 4
bin SKUs)
(Slower with QR DIMMs)
Minimum memory population
1 DIMM 2 DIMMs
(must populate with identical
DIMM pairs)
Hemisphere Mode
No
Yes
Memory RAS Features
ECC, DIMM Sparing, Lock-step,
Mirroring, x4 or x8 SDDC
Enhanced ECC, DIMM sparing,
Lock-step, Mirroring, x4 or x8
SDDC, Rank sparing
PowerEdge R810 and M910
The R810 and M910 servers utilize DDR3 memory providing a high performance, high-speed memory
interface capable of low latency response and high throughput. The R810 and M910 support Registered
DDR3 DIMMs (RDIMMs) only.
The R810 and M910 utilize Intel Xeon 7500 and 6500 series processors that have four SMI channels for
each socket. Each of those memory controllers then has two SMI channels that connect to the Intel
7500 Scalable Memory Buffer.
The DDR3 memory interface consists of eight Intel 7500 Scalable Memory Buffers (two per socket), each
of which has two DDR3 memory channels. Each channel supports up to two RDIMMs for
single/dual/quad rank. By limiting to two DIMMs per DDR channel, the system can support quad-rank
DIMMs at 1066 MTs. The R810 and M910 support a maximum of 32 DIMMS with four SMI channels per
socket, two Intel 7500 Scalable Memory Buffers per SMI channel, and two DDR3 channels per memory
buffer supporting two DIMMs each.
FlexMem Bridge Technology
In a four-CPU configuration, the R810 and M910 use only one memory controller per CPU. This single
controller connects to two memory buffers via SMI links. Each memory buffer in turn connects to four
DDR3 DIMMs with a total of 32 DIMMs accessible. In a two-CPU configuration, normally this would mean
that only four memory buffers are connected; therefore, a total of only 16 DIMMs are accessible.
To overcome this limitation with two CPUs, the R810 and M910 use a pass-through, called the FlexMem
Bridge, in the sockets without CPUs (CPU 3 and CPU 4). This allows CPU 1 and CPU 2 to connect to the
memory of their respective adjacent sockets (CPU 3 and CPU 4) and access the additional 16 DIMMs.
The FlexMem Bridge provides the following:
• Two pass-through links for SMI
• One pass-through link for QPI
• The pass-through SMI links connect the two installed CPUs to additional Intel 7500 Scalable
Memory Buffers; therefore, the CPUs will have the following memory attached:
• CPU 1 will have access to DIMMs A1-A8 and to DIMMs C1-C8 (those normally associated with
CPU 3)
• CPU 2 will have access to DIMMs B1-B8 and to DIMMs D1-D8 (those normally associated with
CPU 4)