Help Me Choose: Memory

 
With the PowerEdge™ R415 and PowerEdge™ R515, you can maximize bandwidth by populating every DIMM slot, regardless of processor model, with 1333 MHz memory. AMD Opteron™ 4100 Series processor-based platforms support two types of DDR3 memory in standard and low voltage offerings:

  • RDIMMs (Registered DIMMs)
    • Supports larger memory sizes
    • Advanced reliability features
  • UDIMMs (Unbuffered ECC DIMMs) 
    • Lower price
    • Slightly lower power

Memory Comparison as currently offered on the R415 and R515

Memory ComparisonUDIMMRDIMM
Register/BufferNoYes
Max Frequency1333MHz1333MHz
Ranks Supported1 or 21, 2 or 4
Capacity per DIMM1,2 or 4GB2,4,8 or 16GB
Max # DIMMs per memory channel22
Total memory per processor16GB64GB
DRAM technologyX8X4 or X8
Temperature SensorYesYes
ECCYesYes
Advanced ECCNox4 Only
Address ParityNoYes
Power (voltage)
1.5V (standard)1.5V (standard)
1.35V (low voltage)1.35V (low voltage)

Speed and Population Dependency

Memory TypesCore Types AvailableMax Capacity per CPUMax Memory Speed(MHz)
Single Rank with (4) DIMMs populated
UDIMM4- and 6-core8GB1333
LV-UDIMM6-core only8GB1333
RDIMM4- and 6-core16GB1333
LV-RDIMM6-core only16GB1333
Dual Rank with (2) DIMMs populated
UDIMM4- and 6-core8GB1333
LV-UDIMM6-core only8GB1333
RDIMM4- and 6-core16GB1333
LV-RDIMM6-core only16GB1333
Dual Rank with (4) DIMMs populated
UDIMM4- and 6-core16GB1066
LV-UDIMM6-core only16GB1066
RDIMM4- and 6-core32GB1066
LV-RDIMM6-core only32GB1066
Quad Rank with (2) DIMMs populated
RDIMM4- and 6-core32GB1066
LV-RDIMM6-core only32GB1066
Quad Rank with (4) DIMMs populated
RDIMM4- and 6-core64GB800
LV-RDIMM6-core only64GB667

Question #1: How can I maximize memory performance?

Answer


  • Populate DIMMs in groups of two, one per channel (2 or 4 per CPU)

Question #2: How can I configure memory to use the least amount of power?

Answer
  • Populate with LV-RDIMM or LV-UDIMM
    • LV-RDIMM is expected to use approximately 20 percent less power per DIMM than RDIMMs
    • LV-UDIMM is expected to use approximately 20 percent less power per DIMM than UDIMMs
  • If the desired memory sized can be achieved, use single ranked DIMMs
  • LV DIMMs are only available with 6-core processors