White Papers

8 Dell EMC NUMA Configuration for AMD EPYC (Naples) Processors | version 1.0
2 Performance Tuning
For best performance from AMD EPYC processors, it is recommended that each die have one DIMM
populated on each channel. This allows all IO behind each die to access memory, with optimal latency.
2.1 Memory DIMM Population Guidelines
 Populate empty channels, with the same type/capacity of DIMMs, before populating 2 DIMMs on a
given channel
 Recommendations for best performance:
o 1 DIMM per channel dedicates full memory bandwidth
o Populating 2 DIMMs per channel will increase capacity but will lower the clock speed,
resulting in lower memory bandwidth. There is a dependency between memory speed and
the bandwidth of the Infinity Fabric
Memory Bus Speed to Infinity Fabric Bud Speed
Memory Bus Speed
Infinity Fabric Speed
(Die to Die within CPU socket)
Infinity Fabric Speed
(Socket-to-Socket)
2666 MT/s
5.3 GT/s
10.6 GT/s
2400 MT/s
4.8 GT/s
9.6 GT/s
2133 MT/s
4.2 GT/s
8.5 GT/s
1866 MT/s
3.7 GT/s
7.4 GT/s
 Minimum recommended:
o At least 1 DIMM is per die in the system for a total of 4 DIMM per CPU
 On Dell EMC platforms populate DIMM 1 first. (white slots in Figure 4, below)
 A 2 socket system (2 CPUs are populated) will need equivalent memory configurations on both CPUs
for optimal performance.