DDR4 ECC RAM

Memory always runs at the lowest of three values: module, CPU and population. With two modules per channel many servers drop one speed step – on 2nd Gen Xeon Scalable typically from 2933 to 2666 MT/s. Peak bandwidth falls by about 9 %, and for virtualisation the extra capacity usually outweighs that.

32 GB or 64 GB DDR4 ECC: planning capacity

In a dual-socket server with 1st or 2nd Gen Xeon Scalable, twelve modules – six per CPU – are the efficient baseline. That gives the usual configurations:

• 12 × 32 GB = 384 GB: the most common build for Proxmox, ESXi or Hyper-V, for example with the Samsung 32 GB DDR4-2933 RDIMM.
• 12 × 64 GB = 768 GB: for databases and dense virtualisation, such as with the SK hynix 64 GB DDR4-2933.
• 24 × 64 GB = 1.5 TB: fills every slot in a Dell R740 and, at 768 GB per socket, stays below the 1 TB limit of standard CPUs.
• 128 GB LRDIMMs: modules such as the Samsung 128 GB DDR4-2666 only make sense when 64 GB per slot isn't enough. On 2nd Gen Xeon Scalable, more than 1 TB per socket requires an M or L CPU.

Xeon E5 v4 has four channels per CPU, so the same logic applies with 8, 16 or 24 modules. AMD EPYC 7002/7003 has eight channels; in a dual-socket server, 16 × 64 GB using the Samsung 64 GB DDR4-3200 is a balanced 1 TB configuration.

Adding DDR4 RDIMMs: step by step

The newest servers, with 4th Gen Xeon Scalable onwards or EPYC 9004, no longer take DDR4; they need DDR5 ECC RAM. Modules you remove can be sold through our buy-back service, with an offer within 48 hours.