Samsung 16GB DDR4 2666MHz ECC Unbuffered Server Memory — M391A2K43BB1-CTDQ

The Samsung M391A2K43BB1-CTDQ is a 16GB DDR4 ECC Unbuffered DIMM (UDIMM) server memory module operating at 2666MHz (PC4-21300) with CAS latency CL19 and 1.2V operating voltage. Unlike registered (buffered) modules, UDIMMs connect directly to the memory controller without a register buffer — delivering lower latency and simpler signal paths for workstation and entry-level server platforms that support ECC UDIMMs. Error-Correcting Code (ECC) technology continuously detects and corrects single-bit memory errors in real time, ensuring data integrity in mission-critical environments.

Key Features

• ECC Unbuffered (UDIMM) Design: Direct connection to memory controller delivers lower latency than RDIMMs — ideal for ECC UDIMM-compatible workstations and entry-level servers
• ECC Error Protection: Real-time single-bit error correction ensures data integrity for mission-critical workloads
• Samsung DRAM: Industry-leading manufacturing quality with proven enterprise-grade reliability and longevity
• RoHS Compliant: Meets global environmental and safety standards for enterprise deployments

Technical Specifications

• Part Number: M391A2K43BB1-CTDQ
• Manufacturer: Samsung
• Memory Type: DDR4 SDRAM
• Module Type: UDIMM ECC (Unbuffered)
• Capacity: 16GB
• Speed: 2666MHz (PC4-21300)
• CAS Latency: CL19
• Timing: 19-19-19
• Voltage: 1.2V
• Form Factor: 288-Pin DIMM
• Rank: Dual Rank (2Rx8)
• Die Organization: x8
• Data Width: 72-bit (64-bit + 8-bit ECC)
• Error Correction: SECDED (Single-bit correction, Double-bit detection)
• Operating Temperature: 0°C to 85°C

Use Cases

• ECC Workstations: AMD Ryzen Pro, Intel Xeon W, and Intel Core with ECC UDIMM support for professional workstation deployments
• Entry-Level Servers: Tower and rack servers supporting ECC UDIMMs for small business and departmental workloads
• NAS and Storage Servers: FreeNAS/TrueNAS, Unraid, and ZFS-based storage platforms requiring ECC memory for data integrity
• Development and Test Systems: ECC-protected development environments requiring lower latency than RDIMM platforms

Compatibility

• Compatible with DDR4 ECC UDIMM slots only — not compatible with RDIMM, LRDIMM, DDR5, or non-ECC UDIMM slots
• CTDQ suffix denotes specific OEM or regional platform qualification — verify against your platform's memory QVL before ordering
• Do not mix ECC UDIMMs with RDIMMs or non-ECC UDIMMs in the same system
• Verify your motherboard or server platform explicitly supports ECC UDIMMs before ordering

Frequently Asked Questions

What is the difference between an ECC UDIMM and an RDIMM?

An ECC UDIMM connects directly to the memory controller without a register buffer, offering lower latency but supporting fewer DIMMs per channel than RDIMMs. RDIMMs use a register buffer to support higher DIMM counts and densities. ECC UDIMMs and RDIMMs are not interchangeable.

What does the CTDQ qualification suffix indicate?

Samsung uses qualification suffixes to denote OEM validation, regional certification, or specific platform testing. CTDQ identifies this module's exact qualification tier — always cross-reference with your platform's memory compatibility or QVL list before purchase.

Can this module run at 2400MHz if my platform does not support 2666MHz?

DDR4 modules are backward speed-compatible — if your platform does not support 2666MHz, the module will train down to the platform's maximum supported speed (e.g., 2400MHz or 2133MHz). Always verify with your platform's QVL to confirm supported configurations.

Whether you are building an ECC-protected workstation, deploying an entry-level server, or expanding a ZFS-based NAS, the Samsung M391A2K43BB1-CTDQ delivers the 16GB DDR4 2666MHz ECC UDIMM reliability, error protection, and Samsung manufacturing quality your platform demands.