HMCG84AHBRA478N - 32GB DDR5-6400 ECC RDIMM | SK Hynix
MPN: HMCG84AHBRA478N ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2072.7273 | $2,072.73 |
| 10 | $1496.9697 | $14,969.70 |
| 100 | $1324.2424 | $132,424.24 |
| 500 | $1266.6667 | $633,333.35 |
| 1,000 | $1209.0909 | $1,209,090.90 |
HMCG84AHBRA478N Overview
A registered DIMM (RDIMM) is a server-class memory module that buffers the command and address signals through a register IC before they reach the DRAM array. This buffering reduces the electrical load on the memory controller, allowing servers to populate more DIMM slots per channel than with unbuffered desktop UDIMMs. RDIMMs sit within the broader hierarchy of synchronous dynamic random-access memory (SDRAM) and are the standard choice in datacenter servers, storage controllers, and virtualization hosts. The x4 DRAM device organization works hand-in-hand with on-die ECC and side-band ECC to correct single-bit errors, improving uptime.
Key features of this module include 6400 MT/s data rate on the DDR5 interface, a CAS latency of 52 clocks, single-rank x4 organization that optimizes register-to-DRAM signal integrity, and the DDR5 standard 1.1V operating voltage, which lowers memory-subsystem power roughly 20-30% versus DDR4 at comparable bandwidth. On-die ECC (ODECC) corrects errors internal to each DRAM die before they propagate onto the module bus.
The HMCG84AHBRA478N uses SK Hynix 1R x4 DDR5 DRAM devices managed by a registered clock driver (RCD), providing deterministic command timing across the 288-pin edge connector. PC5-51200 bandwidth classification corresponds to approximately 51.2 GB/s theoretical peak per module at 6400 MT/s, suiting memory-bandwidth-hungry workloads such as edge compute nodes and low-VM-density virtualization hosts.
Typical applications include general-purpose 2-socket rack servers, edge computing appliances, hyperconverged infrastructure (HCI) nodes, and enterprise storage controllers that specify DDR5-6400 RDIMMs.
When designing or upgrading, always verify that the server platform, BIOS, and CPU memory controller officially support DDR5-6400 RDIMMs; most platforms down-clock to the highest mutually supported JEDEC speed grade if 6400 MT/s is not validated. Mixing ranks, speeds, or vendors within a channel is discouraged.
This page synthesizes distributor availability data, same-brand drop-in alternatives within the SK Hynix HMCG family, and practical deployment notes not found on the manufacturer product page.
Drop-in alternatives for HMCG84AHBRA478N — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with HMCG84AHBRA478N (same form factor and footprint) — differing in Form Factor, Memory Type, Rank.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
HMCG78AHBRA471N
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View Datasheet →HMCG78AHBRA289N
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View Datasheet →HMCG84MEBRA174N
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View Datasheet →HMCG84MEBRA107N
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View Datasheet →HMCG84AGBRA191N
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View Datasheet →HMA84GR7CJR4N-XN
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View Datasheet →HMCG84AHBRA478N Maximum Ratings & Electrical Characteristics
| Manufacturer | SK Hynix |
| Capacity | 32 GB |
| Memory Type | DDR5 SDRAM ECC Registered DIMM (RDIMM) |
| Data Rate | 6400 MT/s |
| PC Rating | PC5-51200 |
| CAS Latency | CL52 |
| Operating Voltage | 1.1 V |
| Rank | Single Rank (1R) |
| DRAM Organization | x4 |
| Module Configuration | 1Rx4 |
| Pin Count | 288-pin |
| Form Factor | 288-pin DIMM (server) |
| ECC | ECC (registered) with DDR5 on-die ECC |
| Bandwidth Class | Approx. 51.2 GB/s per module (theoretical peak) |
| Target Platform | Enterprise server / edge compute |
HMCG84AHBRA478N standard Pin Configuration Guide
Pin configuration for HMCG84AHBRA478N (standard package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for HMCG84AHBRA478N.
Refer to the datasheet for full pin configuration.
Typical Applications
HMCG84AHBRA478N is suitable for 6 applications: General-Purpose 2-Socket Rack Servers, Edge Compute Appliances, Low-VM-Density Virtualization Hosts, Hyperconverged Infrastructure (HCI) Nodes, Enterprise Storage Controllers, AI Inference and Analytics Servers.
General-Purpose 2-Socket Rack Servers
The HMCG84AHBRA478N fits general-purpose enterprise rack servers that specify DDR5-6400 RDIMMs on platforms such as Intel Xeon 6 or AMD EPYC generations validated for 6400 MT/s. Its 6400 MT/s data rate and PC5-51200 classification provide approximately 51.2 GB/s theoretical peak bandwidth per module, while the registered clock driver buffers command/address lines so a single channel can drive multiple DIMMs without signal-integrity degradation. The single-rank x4 organization keeps per-DIMM electrical load low, and DDR5 on-die ECC plus the registered ECC topology protects against single-bit errors that could crash hypervisors or databases. Place identical modules symmetrically across channels to enable full multi-channel bandwidth.
Recommended
Edge Compute Appliances
SK Hynix explicitly positions the HMCG84AHBRA478N for edge compute nodes, where servers operate in constrained spaces with limited cooling and pay strict power budgets. The DDR5 1.1V operating voltage reduces memory-subsystem power roughly 20-30% versus comparable DDR4 capacity at similar bandwidth, and the single-rank x4 configuration minimizes per-module load and heat. At 6400 MT/s the module sustains the bandwidth needed for real-time inference, video analytics, and 5G up-plane processing at the network edge. Deployments should verify ambient temperature ratings on the platform's QVL and ensure airflow across the 288-pin module since edge chassis often lack dedicated DIMM heatsinks.
Recommended
Low-VM-Density Virtualization Hosts
For virtualization hosts running a small number of large, memory-hungry virtual machines, the HMCG84AHBRA478N's 32GB single-rank capacity per slot allows predictable VM sizing without over-provisioning slots. SK Hynix positions this part specifically for low-VM density hosts, where per-VM memory footprint (typically 16-64GB) matters more than raw slot count. The 6400 MT/s data rate shortens memory-latency-bound scheduling stalls, and the x4 organization with ECC registered topology ensures a single DRAM bit error is corrected before it corrupts a guest OS. Use identical modules across all populated channels and enable the platform's memory patrol scrubbing for maximum reliability.
Recommended
Hyperconverged Infrastructure (HCI) Nodes
HCI platforms such as VMware vSAN, Microsoft Azure Local, and Nutanix combine compute, storage, and network functions in each node, making them simultaneously CPU-, memory-, and I/O-intensive. The HMCG84AHBRA478N provides 32GB of DDR5-6400 registered bandwidth per module - about 51.2 GB/s theoretical peak - which supports the distributed storage checksum computation and deduplication workloads that saturate DDR4-3200 memory. The registered ECC topology with x4 devices is required by most HCI platform vendor HCLs for production clusters. Populate nodes with matched 6400 MT/s modules across all eight or twelve channels to avoid degrading the entire channel to the slowest DIMM's speed grade.
Recommended
Enterprise Storage Controllers
RAID controllers, all-flash array heads, and backup appliances rely on host memory for write coalescing, metadata caching, and deduplication tables. The HMCG84AHBRA478N's ECC registered architecture is the standard requirement in these systems because uncorrected bit errors in deduplication metadata can silently corrupt user data. Its 6400 MT/s rate accelerates metadata table traversal compared with DDR5-4800 base modules, improving sustained read/write throughput. Storage OEMs typically qualify exact module suffixes, so verify the full HMCG84AHBRA478N part number appears on the storage platform's compatibility matrix before fleet-wide deployment, and maintain at least one spare module per site for hot-swap replacement.
Recommended
AI Inference and Analytics Servers
AI inference gateways, vector databases, and in-memory analytics servers are memory-bandwidth bound when model weights or columnar datasets are held in host DRAM beside the accelerator. The HMCG84AHBRA478N's 6400 MT/s interface delivers approximately 14% more bandwidth than DDR5-5600 modules, directly increasing token throughput for CPU-side pre/post-processing and embedding lookups. The 32GB single-rank x4 configuration allows high aggregate capacity (for example 2TB with 64 modules on a 12-channel dual-socket platform) while the registered ECC topology meets the reliability bar for always-on inference services. Confirm that the CPU's memory controller officially supports 6400 MT/s RDIMM operation with this rank configuration.
Recommended
Recommended Products Summary
Engineering reference data for HMCG84AHBRA478N — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | HMCG78AHBRA471N | HMCG78AHBRA289N | HMCG84MEBRA174N | HMCG84MEBRA107N | HMA84GR7CJR4N-XN |
|---|---|---|---|---|---|---|
| Package | 288-pin DIMM (RDIMM) | 288-pin DIMM - same | 288-pin DIMM - same | 288-pin DIMM - same | 288-pin DIMM - same | 288-pin DIMM - same |
| Brand | SK Hynix | SK Hynix | SK Hynix | SK Hynix | SK Hynix | SK Hynix |
| Capacity | 32 GB | 32 GB | 32 GB | 32 GB | 32 GB | 32 GB |
| Operating Voltage | 1.1 V | 1.1 V | 1.1 V | 1.1 V | 1.1 V | 1.2 V (DDR4) |
| Memory Generation | DDR5 | DDR5 | DDR5 | DDR5 | DDR5 | DDR4 |
Key Differentiators
- DDR5-6400 top-bin speed grade (vs HMCG78AHBRA471N)
- Single-rank x4 organization (vs HMA84GR7CJR4N-XN)
- Same footprint speed-grade flexibility (vs HMCG84MEBRA174N)
Design Notes
Never mix the HMCG84AHBRA478N (DDR5-6400) with lower-speed RDIMMs (e.g., HMCG78-series DDR5-5600) in the same channel or socket. DDR5 platforms clock every populated channel to the slowest installed module, so one mismatched DIMM degrades all paired channels to its speed grade. Worse, mixing ranks or vendors within a channel frequently causes POST failures or training errors. Populate identical complete MPNs - including the suffix - symmetrically across channels, and match your server's Qualified Vendor List exactly for production deployments.
The complete SK Hynix suffix matters. Memory.net documents the base part HMCG84AHBRA as the same 32GB DDR5-6400 single-rank x4 RDIMM, but the trailing '478N' encodes the SPD profile, revision, and DRAM die generation. OEM-validated platforms (Dell, HPE, Lenovo) qualify exact full MPNs; installing a sibling suffix may work functionally but falls outside the validated configuration and can affect OEM support cases. Always order the exact full part number listed on your platform HCL, and keep the SK Hynix label intact for warranty traceability.
Server RDIMMs at 6400 MT/s dissipate more heat than DDR4-3200 predecessors despite the lower 1.1V rail, because per-module bandwidth roughly doubled. Ensure chassis airflow passes across DIMM slots per the server vendor's thermal guide; most 2U platforms require the DIMM blower to be functional, and thermal throttling of DRAM (reported via SMBus temperature sensors on DDR5 modules) begins well before catastrophic limits. Estimated: doubling data rate approximately doubles dynamic DRAM power, so sustained 6400 MT/s workloads in 40C+ ambient edge enclosures should be derated or use the wide-temperature HMCG78AHBWA315N variant.
DDR5 RDIMMs draw their 1.1V main rail plus a 12V/5V auxiliary rail through the 288-pin edge connector for the PMIC and register IC. Estimated: a fully populated 12-channel, 2-socket server with 24 x 32GB modules adds roughly 100-150W of memory-subsystem load at sustained bandwidth, so verify PSU headroom when upgrading from DDR4. Enable the platform's DIMM power-down and self-refresh idle states in BIOS to reclaim 10-20% of memory power during low utilization, which matters most in edge compute deployments.
Compliance Information
Verified web data did not include explicit RoHS/REACH compliance statements. SK Hynix enterprise DDR5 modules are produced under RoHS/REACH-compliant processes as standard, but obtain the official compliance letter for the exact suffix before procurement sign-off.
