ECC RDIMM Memory | Registered Server RAM Modules – ICD
ECC RDIMM — The Standard for Enterprise Servers
RDIMM (Registered DIMM) is the most widely used server memory type. ICD stocks ECC RDIMM modules in DDR3, DDR4, and DDR5 from Samsung, SK Hynix, Micron, and OEM-branded (Dell, HPE, Lenovo). Capacities from 4GB to 128GB per module.
What is ECC RDIMM?
ECC (Error Correcting Code) detects and corrects single-bit memory errors automatically, preventing crashes and data corruption. Registered means the module has a register chip between the memory chips and the CPU, reducing electrical load and allowing more DIMMs per channel. This is why servers can support 1.5TB-4TB of RAM while desktops max out at 128GB.
RDIMM vs LRDIMM vs UDIMM
| Type | Max Capacity/Module | DIMMs/Channel | Cost | Best For |
|---|---|---|---|---|
| RDIMM | 64GB (DDR4), 96GB (DDR5) | Up to 8 | $$ | Most server workloads (80% of deployments) |
| LRDIMM | 256GB (DDR4), 512GB (DDR5) | Up to 8 | $$$ | Maximum density (databases, in-memory) |
| UDIMM | 32GB | Up to 2 | $ | Entry-level towers only (T140, ML30) |
Available Capacities & Speeds
| Generation | Capacities | Speeds |
|---|---|---|
| DDR5 RDIMM | 16GB, 32GB, 64GB, 96GB | 4800MHz, 5600MHz |
| DDR4 RDIMM | 8GB, 16GB, 32GB, 64GB | 2133, 2400, 2666, 2933, 3200MHz |
| DDR3 RDIMM | 4GB, 8GB, 16GB, 32GB | 1333, 1600, 1866MHz |
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Frequently Asked Questions
What is the difference between ECC and non-ECC RAM?
ECC (Error Correcting Code) RAM can detect and correct single-bit memory errors in real-time. Non-ECC RAM cannot. Servers require ECC memory because undetected memory errors in a production environment can cause data corruption, crashes, and security vulnerabilities.
Can I use RDIMM and LRDIMM together?
No. You cannot mix RDIMM and LRDIMM in the same server. All memory modules must be the same type. However, you can mix capacities (e.g., 16GB and 32GB RDIMMs) in some configurations, though matching is recommended for optimal performance.