5
Memory
The C6420 supports up to 16 DIMMs, with speeds of up to 2666MT/s. The system supports registered (RDIMMs) and load reduced
DIMMs (LRDIMMs) which use a buffer to reduce memory loading and provide greater density, allowing for the maximum platform
memory capacity. Unbuffered DIMMs (UDIMMs) are not supported.
The maximum system population is 2TB (16 DIMM slots x128 GB DDR4 LRDIMM), however for best performance the system should
be populated to achieve a balanced configuration by populating 1 DIMM per channel. In a balanced configuration with maximum
capacity, 12 DIMM slots are populated for a total of 1.5TB memory using 128GB DIMMs.
Supported memory
The following table list the supported memory for the PowerEdge C6420 when using Cascade Lake processor:
Availability
Density DIMM Type Dell PN
Configuration
DRAM
Package
type
DIMM max speed
Rated
voltage
Yes
8GB
RDIMM
1VRGY
1Rx8
8Gb
SDP
2666MT/s in Cascade
Lake processor
1.2V
Yes
16GB
RDIMM
TFYHP
2Rx8
8Gb
SDP
2933MT/s
1.2V
Yes
32GB
RDIMM
8WKDY
2RX4
8Gb
SDP
2933MT/s
1.2V
Yes
64GB
RDIMM
W403Y
4Rx4
8Gb
DDP
2933MT/s
1.2V
Yes
128GB
LRDIMM
917VK
8Rx4
8Gb
TSV
2666MT/s in Cascade
Lake processor
1.2V
Memory speed
The PowerEdge C6420 system supports memory speeds of 2933MT/s, 2666MT/s, 2400MT/s, 2133MT/s, and 1866MT/s depending
on the DIMM types installed and the configuration. All memory on all processors and channels run at the same speed and voltage. By
default, this speed will be the highest speed supported by the CPU and the DIMMs. For example both DIMMs and CPUs must be
capable of running at 2666MT/s in order for memory to run at 2666MT/s (specific CPU / DIMM configuration required). CPU SKUs
in the Platinum category support up to 2666MT/s memory speed while CPU SKUs in Gold and Silver category support up to 2400
MT/s memory speed. The operating speed of the memory is also determined by the maximum speed supported by the processor,
the speed settings in the BIOS, and the operating voltage of the system.
The table below lists the memory configuration and performance details for the Mercury, based on the quantity and type of DIMMs
per memory channel.
DIMM type
DIMM ranking
Capacity
DIMM rated voltage,
speed
1 DPC
RDIMM
1R / 2R
8GB, 16GB, 32GB
DDR4 (1.2V), 2666
D: 2666
LRDIMM
4R
64GB
DDR4 (1.2V), 2666
D: 2666
LRDIMM
8R
128GB
DDR4 (1.2V), 2666
D: 2666
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