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Four green circuit boards with gold edge connectors and black chips, no heat spreaders

OWC

OWC 64GB (4x16GB) DDR4 2666MHz ECC UDIMM memory upgrade

SKU CH-PB5M-3EJJ3

Four 16 GB DDR4 2666 ECC UDIMM modules add 64 GB of error-correcting memory to Synology RackStation RS3617RPxs and RS3617xs+ systems

  • Total capacity64 GB (4 × 16 GB)
  • Rated speedDDR4 2666 (PC4 21300)
  • CAS latencyCL19
  • Rated voltage1.2 V
  • Buffer typeUnbuffered
  • Memory rank2Rx8

Capacity 64GB (4 x 16GB)

  • 64GB total capacity lets you run more VMs and containers
  • Four 16GB modules populate all slots for maximum throughput
  • DDR4 2666MHz CL19 delivers responsive NAS performance
  • ECC unbuffered design protects data integrity in critical workloads
  • JEDEC-standard 1.2V operation keeps power draw low

Synology RackStation memory upgrade

This 64GB kit contains four 16GB DDR4 2666MHz ECC unbuffered UDIMMs built for Synology RackStation RS3617RPxs and RS3617xs+ systems. It delivers 64GB of error-correcting memory at PC4-21300 speed with CL19 latency and 1.2V operation. The modules are JEDEC-standard and RoHS-compliant for warranty-safe installation.

Thermals and power draw

Each module runs at 1.2V without a heat spreader, relying on the chassis airflow of the target RackStation units. The DDR4 2666MHz JEDEC voltage keeps power draw low during continuous NAS workloads such as file serving, virtualization or surveillance recording. No active cooling is required on the DIMMs themselves.

What the kit changes

Adding 64GB of ECC memory lets the compatible RackStation models handle larger ZFS caches, more concurrent Docker containers and heavier virtual-machine workloads without data-corruption risk. The four-module population fills all slots for maximum dual-channel bandwidth. Systems originally equipped with 2133MHz or 2400MHz memory will run the new modules at the lower supported speed.

How it compares

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

Price $490.99
Typical for this category: the median of 21,161 items is $397.99.
Total capacity 64 GB (4 × 16 GB)
Higher than about 60% of the 20,941 comparable items (median 32 GB).
Price per GB $7.67 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 number2E6D42R8064S
Total capacity64 GB (4 × 16 GB)
Product type288-Pin DDR4 ECC UDIMM
Performance
Rated speedDDR4 2666 (PC4 21300)
Memory
CAS latencyCL19
ECC supportYes
Buffer typeUnbuffered
Memory rank2Rx8
Heat spreaderNo
Power
Rated voltage1.2 V
Compatibility
Compatible systemsSynology RackstationRS3617RPxs
Synology RackstationRS3617xs+

Other versions of this model

5 more in the same range

Questions about this item

How do I install the 4x16GB DDR4 2666 ECC UDIMM kit in my Synology RS3617RPxs, and what step do people often miss?

Power down the NAS, open the chassis, and seat all four 288-pin modules firmly until the retention clips click; the step most people miss is verifying in DSM that all 64GB are recognised at 2666MHz CL19 before closing the case.

What maintenance or replacement will this ECC UDIMM kit need over its service life?

No scheduled maintenance is required; the modules run at 1.2V without heat spreaders, so only a future capacity upgrade or a confirmed module failure would prompt replacement.

What limit appears first when the Synology RS3617xs+ runs this 64GB kit under sustained heavy workloads?

The memory controller caps operation at DDR4 2666 CL19, so sustained throughput is limited to the PC4-21300 bandwidth ceiling rather than thermal or voltage headroom.

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