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Two green DDR4 ECC UDIMM sticks, gold contacts, no heat spreader

OWC

OWC 16GB (2x8GB) DDR4 2666MHz ECC UDIMM memory upgrade

SKU CH-4RX5-F09M5

ECC UDIMM kit adds 16 GB of DDR4 2666 CL19 memory to compatible Synology RackStation NAS models

  • Total capacity16 GB (2 × 8 GB)
  • Rated speedDDR4 2666 (PC4 21300)
  • CAS latencyCL19
  • Rated voltage1.2 V
  • Buffer typeUnbuffered
  • Memory rank1Rx8

Capacity 16GB (2 x 8GB)

  • 16 GB kit (2 × 8 GB) expands NAS capacity
  • DDR4 2666 MHz CL19 delivers fast data throughput
  • ECC unbuffered design protects data integrity
  • 2 V low voltage reduces power draw
  • Validated for Synology RS2421+ and RS2421RP+

OWC 16GB DDR4 2666MHz ECC kit

This 16GB kit contains two 8GB DDR4 2666MHz ECC UDIMM modules built for Synology RackStation RS2421+ and RS2421RP+ systems. It targets administrators who need error-correcting memory to protect data integrity in NAS workloads. The unbuffered design fits the qualified platforms without registration overhead.

Capacity and headroom for NAS workloads

Sixteen gigabytes expands the memory pool available for file caching, virtual machines and containerised services on the supported RackStation units. The dual-rank 1Rx8 organisation and CL19 latency deliver stable throughput for typical multi-user access patterns. Workloads that exceed 16GB will still page to storage, so larger datasets need additional modules or a platform with higher maximum capacity.

DDR4 2666MHz interface limits

The modules operate at the JEDEC-standard DDR4 2666 (PC4-21300) data rate and fall back to 2400MHz or 2133MHz when the memory controller requires it. ECC parity generation adds a small latency penalty compared with non-ECC UDIMMs at the same frequency. The 288-pin unbuffered form factor cannot be used in registered or load-reduced DIMM slots, so platform compatibility must be verified before purchase.

How it compares

Measured against everything we stock in Model-Specific Memory Upgrades, at today’s prices. Recalculated every night.

Price $120.99
Cheaper than about 65% of the 21,161 comparable items (median $397.99).
Total capacity 16 GB (2 × 8 GB)
Lower than about 70% of the 20,941 comparable items (median 32 GB).
Price per GB $7.56 per GB
Typical for this category: the median of 20,941 items is $8.19 per GB.

New to this? Buying memory and SSDs with crypto — what to check, what it costs to pay, and what is never asked for.

Specifications

Product
Brand nameOWC
Part number2E6D41R8016P
Total capacity16 GB (2 × 8 GB)
Product type288-Pin DDR4 ECC UDIMM
Performance
Rated speedDDR4 2666 (PC4 21300)
Memory
CAS latencyCL19
ECC supportYes
Buffer typeUnbuffered
Memory rank1Rx8
Heat spreaderNo
Power
Rated voltage1.2 V
Compatibility
Compatible systemsSynology RackstationRS2421+
Synology RackstationRS2421RP+

Other versions of this model

5 more in the same range

Questions about this item

Will this DDR4 2666 kit run alongside my existing 2133MHz or 2400MHz modules in the Synology RS2421+?

The kit is backward compatible with 2133MHz and 2400MHz speeds, so it will downclock to match slower modules already installed.

How can I verify the ECC UDIMM is recognised correctly after installation?

Open Synology DSM and check the Info Center or Resource Monitor; they will display the new 16GB total and confirm ECC is active.

Does the package contain only the two 8GB sticks or are tools and cables included?

The box contains the two 288-pin DDR4 ECC UDIMM modules; no tools, cables or heat spreaders are supplied.

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