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Four green DDR4 UDIMM modules, no heat spreaders, 288 pins each

OWC

OWC 64GB (4x16GB) DDR4 2666MHz ECC UDIMM CL19 1.2V for Synology RS4017xs+ RS4021xs+

SKU CH-MXCX-RCFA8

A 64GB kit of four 16GB DDR4 2666MHz ECC UDIMM modules at 1.2V CL19, validated for Synology RS4017xs+ and RS4021xs+

  • 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 with four 16GB modules for expanded NAS multitasking
  • DDR4 2666MHz CL19 speed matching Synology RS4017xs+ and RS4021xs+ specifications
  • ECC unbuffered design protects data integrity in critical storage workloads
  • JEDEC-standard 1.2V operation ensures warranty-safe compatibility with Synology RackStation systems
  • Backward compatible with 2133MHz and 2400MHz platforms for flexible deployment

Synology RackStation memory kit

This 64GB kit contains four 16GB DDR4 2666MHz ECC UDIMM modules built for the Synology RS4017xs+ and RS4021xs+. It targets administrators who need to expand system memory for virtualization, database workloads or heavy multi-user file services on those specific platforms.

288-pin unbuffered ECC design

Each module uses a standard 288-pin UDIMM form factor with 2Rx8 organisation and runs at 1.2V. The unbuffered layout fits directly into the RackStation memory slots without registered buffering, while on-die ECC protects data integrity in always-on NAS environments.

JEDEC and RoHS compliant modules

The memory meets JEDEC DDR4 specifications and RoHS requirements, ensuring a warranty-safe upgrade for the supported Synology systems. Backward compatibility with 2133MHz and 2400MHz bus speeds allows the kit to operate reliably if the platform negotiates a lower frequency.

How it compares

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

Price $492.99
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 $7.70 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 RackstationRS4017xs+
Synology RackstationRS4021xs+

Other versions of this model

5 more in the same range

Questions about this item

What speed does the DDR4 2666MHz interface run at in a Synology RS4017xs+?

The modules run at 2666 MHz; the system will clock them down to 2133 MHz or 2400 MHz if the platform requires a lower speed.

How many 288-pin UDIMM slots must be free to install this 64 GB kit?

Four empty 288-pin DDR4 UDIMM slots are needed because the kit contains four 16 GB modules.

Which way round do the 2Rx8 ECC modules go into the RackStation slots?

Align the notch on each 288-pin DIMM with the key in the slot, press straight down until both side clips click, and repeat for all four modules.

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