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Four green DDR4 RDIMM modules, 288-pin, no heat spreader

OWC

OWC 128GB (4x32GB) DDR4 2666 ECC Registered RDIMM

SKU CH-5FR3-083XR

A 128 GB DDR4-2666 ECC registered quad-channel kit of four 32 GB RDIMMs for compatible servers and NAS systems

  • Total capacity128 GB (4 × 32 GB)
  • Rated speedDDR4 2666 (PC4 21300)
  • CAS latencyCL19
  • Rated voltage1.2 V
  • Buffer typeRegistered
  • Memory rank2Rx4

Capacity 128GB (4 x 32GB)

  • 128GB total capacity from four 32GB modules for high-density server workloads
  • ECC registered operation detects and corrects data errors to protect critical applications
  • DDR4 2666MHz CL19 at 1.2V delivers JEDEC-standard performance with low power draw
  • Backward compatible with 2133MHz and 2400MHz systems for flexible deployment
  • 288-pin RDIMM form factor fits compatible workstation, server and NAS platforms

Target System Compatibility

This kit provides 128GB of DDR4 2666 ECC Registered memory across four 32GB modules. It is built for servers, workstations and NAS platforms that require registered DIMMs. Standard desktop computers cannot use this memory because they lack the necessary memory controller support.

Sustained Workload Behaviour

ECC circuitry corrects single-bit errors in real time, protecting data integrity during long compute or storage tasks. Registered buffering reduces electrical load on the memory controller, allowing all four modules to run at the rated 2666 MT/s without signal degradation. The kit is also backward compatible with 2133 and 2400 MT/s systems.

Installation Notes

Each module uses the standard 288-pin DDR4 form factor and operates at 1.2V, so it fits any DDR4 RDIMM slot. The registered design means it must not be mixed with unbuffered or load-reduced DIMMs; doing so will prevent the system from posting. No heat spreaders are present, so clearance is minimal.

How it compares

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

Price $812.99
Pricier than about 77% of the 6,523 comparable items (median $188.99).
Total capacity 128 GB (4 × 32 GB)
Higher than about 90% of the 6,064 comparable items (median 32 GB).
Price per GB $6.35 per GB
Cheaper than about 60% of the 6,064 comparable items (median $7.25 per GB).

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Specifications

Product
Brand nameOWC
Part number2R6D42R4128S
Total capacity128 GB (4 × 32 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

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Questions about this item

How much power does the 1.2V DDR4 2666 kit draw when the Synology SA6400 runs continuously?

Each module operates at 1.2V, the standard DDR4 voltage, so total draw stays within the platform's registered DIMM power budget for 24/7 NAS workloads.

What must the Synology FlashStation SA6400 already have to accept this 4×32GB ECC registered kit?

The SA6400 needs free 288-pin DDR4 slots that support registered ECC DIMMs; the system's memory controller must be configured for registered modules, not unbuffered or load-reduced types.

Will these 2666MHz CL19 modules run stably alongside existing 2133MHz or 2400MHz DIMMs in the same server?

Yes, the kit is backward compatible with 2133MHz and 2400MHz speeds; all populated slots will run at the lowest common frequency and matched timings.

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