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Four green 288-pin DDR4 RDIMM modules in a clear tray

OWC

OWC 256GB (4x64GB) DDR4 2666 ECC Registered RDIMM server RAM

SKU CH-W492-JM43W

256 GB DDR4 2666 ECC registered RDIMM kit of four 64 GB modules for servers and compatible Synology NAS

  • Total capacity256 GB (4 × 64 GB)
  • Rated speedDDR4 2666 (PC4 21300)
  • CAS latencyCL19
  • Rated voltage1.2 V
  • Buffer typeRegistered
  • Memory rank2Rx4

Capacity 256GB (4 x 64GB)

  • 256 GB total capacity from four 64 GB modules
  • DDR4 2666 MHz speed with CL19 latency
  • ECC registered design for server error correction
  • JEDEC and RoHS compliant for warranty-safe upgrades
  • Backward compatible with 2133 MHz and 2400 MHz systems

Server memory upgrade kit

This 256GB kit contains four 64GB DDR4 2666 ECC Registered RDIMM modules designed for servers, workstations and compatible NAS systems such as the Synology FlashStation SA6400. It replaces the Synology D4ER01-64G part and runs at 1.2V with CL19 latency.

Installation notes

Modules use the standard 288-pin DDR4 form factor and are keyed to prevent incorrect insertion. Because they are registered ECC DIMMs they will not work in standard desktop motherboards and must not be mixed with unbuffered or load-reduced memory. Backward compatibility with 2133MHz and 2400MHz systems is supported.

Pre-purchase checks

Verify that your platform accepts DDR4 288-pin ECC Registered RDIMMs and supports 2Rx4 rank configuration. Confirm the maximum memory capacity per slot and total system limit in your hardware documentation. Ensure all four slots can be populated identically for the dual-channel kit to operate as intended.

How it compares

Measured against everything we stock in ECC Server RAM, at today’s prices. Recalculated every night.

Price $1,435.99
Pricier than about 83% of the 6,523 comparable items (median $188.99).
Total capacity 256 GB (4 × 64 GB)
Higher than about 90% of the 6,064 comparable items (median 32 GB).
Price per GB $5.61 per GB
Cheaper than about 68% of the 6,064 comparable items (median $7.25 per GB).

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Specifications

Product
Brand nameOWC
Part number2R6D42R4256S
Total capacity256 GB (4 × 64 GB)
Product type288-Pin DDR4 SDRAM
Performance
Rated speedDDR4 2666 (PC4 21300)
Memory
CAS latencyCL19
ECC supportYes
Buffer typeRegistered
Memory rank2Rx4
Kit configurationDual Channel Kit
Heat spreaderNo
Power
Rated voltage1.2 V

Other versions of this model

5 more in the same range

Questions about this item

How do I confirm the 256GB kit is running at 2666 MHz CL19 after installation?

Check the BIOS or UEFI memory section — it should report DDR4 2666 (PC4-21300) with CAS latency 19 for all four modules.

What comes in the box and what else is needed?

The kit includes four 64 GB 288-pin DDR4 ECC Registered RDIMMs; no extra parts are required if your server or NAS has four compatible DIMM slots.

Which capacity version should I choose for a Synology SA6400 that supports 256 GB maximum?

This 256 GB (4 × 64 GB) kit matches the SA6400's maximum supported memory and fills all four slots for dual-channel operation.

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