Dell PowerEdge R940 - Supported Memory; Memory Speed and Configuration

Supported Memory
The PowerEdge R940 supports up to 48 DIMM slots, with up to 6 TB of memory and speeds up to 2666 MT/s. Supported DIMMs are
registered (RDIMMs) and load reduced (LRDIMMs) DIMMs which uses a buer to reduce memory loading and provide greater density
allowing maximum memory capacity.
Memory speed
The PowerEdge R940 supports memory speeds of 2666 MT/s, 2400 MT/s, and 1866 MT/s depending on the DIMM types installed and
congured. All memory on all of the processors and channels run at the same speed and voltage. The operating speed of the memory is
determined by the maximum speed supported by the processor, the speed settings in BIOS, and the operating voltage of the system.
Table 6. Memory conguration based on quantity and quality of DIMM
DIMM type DIMM ranking Capacity DIMM rated voltage
and speed
Max speed (MT/s) on 1
DPC
Max speed (MT/s) on
2 DPC
RDIMM 1R/2R 8 GB, 16 GB, 32 GB DDR4 (1.2 V), 2666
MT/s
2666 2666
LRDIMM 4R/8R 64 GB, 128 GB DDR4 (1.2 V), 2666
MT/s
2666 2666
Memory congurations and population rules
The R940 supports exible memory congurations ranging from 8 GB (minimum) to 128 GB (maximum). The R940 supports up to 12
DIMMs per processor or 24 DIMMs in a dual-processor and 48 DIMMs in a quad-processor conguration. Each R940 has 6 memory
channels per processor, with each channel supporting up to 2 DIMMs.
The R940 server support exible memory conguration according to the following population rules:
• If DIMMs of dierent speeds are mixed, all channels across all processors operate at the slowest DIMM's common frequency.
• DIMM type:
• All DIMMs must be DDR4 RDIMM and LRDIMM
• Only one type of DIMM is allowed per system-RDIMM, or LRDIMM. They cannot be mixed.
• DIMMs with dierent data width (x4 and x8 data width) can be mixed.
• The largest DIMM capacity is placed rst (slot A1 rst, then A2 and so on). The second CPU mirrors the rst CPU population rule.
• Maximum of two dierent capacity DIMMs are allowed in the system.
• Maximum of two dierent rank DIMMs are allowed in the system.
Table 7. DIMM mixing support
DIMM types RDIMM LRDIMM 3DS LRDIMM
RDIMM allowed not allowed not allowed
LRDIMM not allowed allowed not allowed
3DS LRDIMM not allowed not allowed allowed
5
Supported Memory 17