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Two green DDR4 RDIMM modules with gold edge connectors and black chips

OWC

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

SKU CH-J84C-096WY

A 64GB dual-channel kit of DDR4 2666 ECC registered RDIMMs for servers, workstations and compatible NAS systems

  • Capacity64GB (2 x 32GB)
  • Type288-Pin DDR4 SDRAM
  • SpeedDDR4 2666 (PC4 21300)
  • CAS LatencyCL19
  • Voltage1.2V
  • ECCYes

Capacity 64GB (2 x 32GB)

Rank 2Rx4

  • 64 GB dual-channel kit expands server memory capacity
  • ECC registered design detects and corrects data errors
  • DDR4 2666 CL19 at 1.2 V delivers rated speed
  • JEDEC and RoHS compliant for warranty-safe upgrades
  • Compatible with Synology FS6400 and HD6500 NAS systems

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.

Highlights

  • 64 GB dual-channel kit expands server memory capacity
  • ECC registered design detects and corrects data errors
  • DDR4 2666 CL19 at 1.2 V delivers rated speed
  • JEDEC and RoHS compliant for warranty-safe upgrades
  • Compatible with Synology FS6400 and HD6500 NAS systems

Specifications

BrandOWC
Part Number2R6D42R4064P
Capacity64GB (2 x 32GB)
Type288-Pin DDR4 SDRAM
SpeedDDR4 2666 (PC4 21300)
CAS LatencyCL19
Voltage1.2V
ECCYes
Buffered/RegisteredRegistered
Rank2Rx4
Multi-channel KitDual Channel Kit
Heat SpreaderNo

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Questions about this item

Does the DDR4 2666 interface cap the speed at 2666 MT/s even if the board supports higher?

Yes, the modules run at PC4-21300 2666 MHz CL19; they also operate at 2133 MHz and 2400 MHz if the system requires those speeds.

What physical slot and module dimensions does this 288-pin RDIMM kit require?

Each 32 GB stick uses the standard 288-pin DDR4 RDIMM form factor with no heat spreader, so it fits any server or workstation slot that accepts registered ECC DIMMs.

How is the dual-channel kit installed and what step do people often miss?

Insert both modules into the correct paired slots for dual-channel operation, ensure the registration notch aligns, and verify the BIOS recognises the full 64 GB as registered ECC memory.

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