Specifications

18 PowerEdge R420 Technical Guide
The R420 supports the DIMMs listed in Table 8. For the latest information on supported memory,
visit Dell.com/PowerEdge.
Table 8. DIMMs supported
Capacity
(GB)
Speed
(MT/s)
Type
Ranks per
DIMM
Data
width
SDDC support
Voltage
2
1600
UDIMM
1
x8
Advanced ECC
1.35
2
1600
RDIMM
1
x8
Advanced ECC
1.35
4
1600
RDIMM
2
x8
Advanced ECC
1.35
4
1600
UDIMM
1
x8
Advanced ECC
1.35
4
1600
UDIMM
2
x8
Advanced ECC
1.35
4
1600
RDIMM
1
x8
Advanced ECC
1.35
8
1600
RDIMM
1
x4
All modes
1.35
8
1600
RDIMM
2
x4
All modes
1.35
16
1600
RDIMM
2
x4
All modes
1.35
16
1600
RDIMM
2
x4
All modes
1.35
32
1333
RDIMM
4
x4
All modes
1.35
Memory configurations
Flexible memory configurations are supported on the R420, ranging from capacities of 2GB to
384GB. The system supports up to six DIMMs per processor (up to 12 DIMMs in a two-processor
configuration). The R420 has three memory channels per processor, with each channel supporting
up to two 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 Dell.com/Support/Manuals.