OWC 64GB (2x32GB) DDR4 2666 ECC Registered RDIMM Server Memory

Synology NAS Upgrade Kit

This 64 GB kit consists of two 32 GB DDR4 2666 ECC registered RDIMM modules built as direct replacements for Synology part numbers D4RD-2666-32G and D4ER01-32G. It targets administrators upgrading FlashStation FS6400 or HD6500 systems who need validated server-grade memory. The dual-channel configuration is intended for workstation and NAS platforms that require registered DIMMs with error correction.

Registered DIMM Build Implications

Each module uses a 288-pin DDR4 form factor with a 2Rx4 organisation and operates at 1.2 V without a heat spreader. The registered design adds a buffer that reduces electrical load on the memory controller, a requirement for the target Synology platforms. Because the modules are registered ECC, they cannot be mixed with unbuffered or load-reduced memory and will not function in standard desktop computers that lack registered DIMM support.

JEDEC Compliance and Backward Compatibility

The kit meets JEDEC and RoHS standards, providing a warranty-safe upgrade path for the listed Synology models. Backward compatibility with 2133 MHz and 2400 MHz systems allows the same modules to run at lower speeds if the platform requires it. The manufacturer includes a limited lifetime warranty with free technical support and an advanced replacement programme for the memory modules.