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Four green DDR4 ECC UDIMM modules with gold contacts and black chips

NEMIX RAM

NEMIX RAM 64GB (4x16GB) DDR4 2666 ECC UDIMM Synology RackStation RS4021xs+ memory upgrade

SKU CH-T2QZ-H60VA

A 64 GB kit of four 16 GB DDR4 2666 ECC UDIMM modules at 1.2 V CL19 for Synology RackStation RS4021xs+ NAS upgrades

  • Total capacity64 GB (4 × 16 GB)
  • Rated speedDDR4 2666 (PC4 21300)
  • ChipsetMajor OEM Samsung, Micron, Hynix
  • CAS latencyCL19
  • Buffer typeUnbuffered
  • Rated voltage1.2 V
  • 64 GB total capacity in a four-module kit
  • DDR4 2666 speed rated at PC4-21300 bandwidth
  • ECC protection detects and corrects single-bit errors
  • 2 V low-voltage operation reduces power draw
  • Validated for Synology RackStation RS4021xs+ compatibility

Synology RS4021xs+ 64GB kit

This 64GB kit supplies four 16GB DDR4 2666 ECC unbuffered UDIMMs validated for the Synology RackStation RS4021xs+. It targets administrators who need to expand NAS memory for virtualisation, container workloads or large file caches without mixing module capacities.

Thermals noise and power

Each module runs at 1.2V with no heat spreader, relying on the chassis airflow of the RS4021xs+ for cooling. The low-voltage DDR4 design keeps power draw modest during sustained workloads, and the unbuffered layout adds no active components that would increase acoustic output.

ECC and rank configuration

On-die ECC detects and corrects single-bit errors to protect data integrity in always-on storage services. The 2Rx8 organisation populates all four slots with dual-rank modules, delivering the full 64GB capacity in a single matched kit that simplifies installation and avoids rank-mismatch issues.

How it compares

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

Price $527.99
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 $8.25 per GB
Typical for this category: the median of 20,941 items is $8.19 per GB.

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Specifications

Product
Brand nameNEMIX RAM
Product lineSynology Compatible Series NAS Memory
Model nameSynology DDR4 2666 MHz ECC Unbuffered UDIMM
Part numberME21300-628K4
Total capacity64 GB (4 × 16 GB)
Product type288-Pin DDR4 ECC UDIMM
Performance
Rated speedDDR4 2666 (PC4 21300)
Processor
ChipsetMajor OEM Samsung, Micron, Hynix
Memory
CAS latencyCL19
ECC supportYes
Buffer typeUnbuffered
Heat spreaderNo
Memory rank2Rx8
Power
Rated voltage1.2 V
Compatibility
Compatible systemsSynology
In the box
Included items64 GB (4 × 16 GB) DDR4 2666 MHz PC4-21300 2Rx8 1.2 V CL19 288-PIN ECC Unbuffered UDIMM KIT

Questions about this item

How do I install the 4x16GB DDR4 2666 ECC UDIMM kit in my Synology RS4021xs+, and what step is often missed?

Power off the NAS, open the chassis, insert each 288-pin module firmly until the retention clips click, then verify all four 16GB sticks are recognised in DSM before closing the case.

What maintenance or replacement will the 64GB ECC UDIMM kit need over its service life?

No scheduled maintenance is required; ECC corrects single-bit errors on the fly, and the modules carry a lifetime replacement warranty if a hardware fault ever develops.

What limit appears first when the RS4021xs+ runs sustained workloads with this 2666 CL19 1.20V memory?

The memory controller caps throughput at DDR4 2666 (PC4-21300), so bandwidth — not voltage or latency — becomes the bottleneck during prolonged heavy use.

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