Specifications

The R420 supports the DIMMs listed in Table 8. For the latest information on supported memory,
visit Dell.com.
Capacity
(GB)
Speed
(MT/s)
Type
Ranks per
DIMM
Data
width
SDDC support
Voltage
2
1333
RDIMM
1
x8
Advanced ECC
1.35
2
1333
UDIMM
1
x8
Advanced ECC
1.35
2
1600
RDIMM
1
x8
Advanced ECC
1.5
4
1333
RDIMM
2
x8
Advanced ECC
1.35
4
1333
RDIMM
1
x4
All modes
1.35
4
1333
UDIMM
2
x8
Advanced ECC
1.35
4
1600
RDIMM
2
x8
Advanced ECC
1.5
8
1333
RDIMM
2
x4
All modes
1.35
8
1600
RDIMM
2
x4
All modes
1.5
16
1333
RDIMM
2
x4
All modes
1.35
16
1600
RDIMM
2
x4
All modes
1.5
Flexible memory configurations are supported on the R420, ranging from capacities of 2 GB to
192 GB. The system supports up to 6 DIMMs per processor (up to 12 DIMMs in a 2-processor
configuration). The R420 has 3 memory channels per processor, with each channel supporting up
to 2 DIMMs.
The R420 supports a flexible memory configuration according to these 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 can be used in a system. UDIMMs and RDIMMs cannot be
mixed.
The following additional memory population guidelines apply to the R420:
 Up to two quad-rank (QR), dual-rank (DR), or single-rank (SR) DIMMs may be populated 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, see the Dell PowerEdge R420 Systems Owner’s
Manual on Support.Dell.com/Manuals.
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