HMA41GR7MFR8N-TF Datasheet, Pinout, Equivalents, and Specs

The HMA41GR7MFR8N-TF is an 8GB DDR4-2133MHz Registered Dual In-Line Memory Module (RDIMM) manufactured by SK Hynix, engineered specifically for enterprise server and high-performance workstation environments. Operating at a standard VDD of 1.2V and utilizing a 1Rx4 (Single Rank x4) organization, this module adheres strictly to JEDEC PC4-2133P specifications. It integrates a Registering Clock Driver (RCD) and Error-Correcting Code (ECC) to ensure signal integrity and data reliability across high-density memory channels.

What is the HMA41GR7MFR8N-TF?

The HMA41GR7MFR8N-TF represents a critical component in the SK Hynix DDR4 server memory portfolio, utilizing the company's M-die silicon architecture. As an 8GB RDIMM, it is constructed using eighteen 4Gb (Gigabit) DDR4 SDRAM components in a FBGA (Fine-Pitch Ball Grid Array) package, arranged in a 1Rx4 configuration. The "x4" designation indicates that each DRAM chip provides a 4-bit data width, which is a standard requirement for advanced ECC algorithms like Chipkill that can detect and correct multi-bit errors within a single DRAM package.

At the core of the HMA41GR7MFR8N-TF's architecture is the Registering Clock Driver (RCD). Unlike Unbuffered DIMMs (UDIMMs) where the memory controller interfaces directly with the DRAM chips, the RCD on this module acts as a buffer for the Command (CMD), Address (ADD), and Clock (CLK) signals. By isolating the DRAM components from the memory bus, the RCD significantly reduces the electrical loading on the host processor's memory controller. This reduction in capacitive load is what allows enterprise servers to populate multiple DIMMs per channel without degrading signal integrity or requiring unmanageable voltage increases.

Operating at 2133 MT/s (MegaTransfers per second), the module provides a peak theoretical bandwidth of 17.0 GB/s per channel. The internal architecture of the DDR4 SDRAM components features an 8n-bit prefetch buffer and is divided into 16 internal banks (organized as 4 bank groups of 4 banks each). This bank group architecture allows for faster concurrent operations; an access to a different bank group requires shorter timing delays (tCCD_S) compared to accessing a bank within the same group (tCCD_L). Furthermore, the module utilizes Pseudo-Open Drain (POD) I/O signaling, which reduces power consumption during data transmission by only drawing current when driving a logical "0", a significant architectural shift from the SSTL I/O used in DDR3.

Pinout Configuration and Packaging

The HMA41GR7MFR8N-TF utilizes the JEDEC-standard 288-pin edge connector designed for DDR4 memory slots. The physical PCB features a curved edge design, which reduces the insertion force required during installation and minimizes mechanical stress on the motherboard's DIMM socket. The pin pitch is 0.85mm, and the module includes a specific key (notch) placement that physically prevents insertion into incompatible DDR3 or DDR5 slots.

The pinout is meticulously organized to optimize signal integrity and power delivery. The primary power pins include VDD (1.2V for core and I/O), VPP (2.5V for wordline activation), and VSS (Ground). The introduction of the VPP pin in DDR4 is a critical architectural change; by providing a dedicated 2.5V rail for the DRAM wordline boost, the primary VDD rail can be lowered to 1.2V without requiring internal charge pumps, thereby reducing overall module power consumption and thermal dissipation.

Signal pins are divided into several functional groups. The Command and Address (CA) pins are routed directly to the RCD, which then regenerates and distributes these signals to the individual DRAM packages. The Data (DQ) and Data Strobe (DQS) pins bypass the RCD and connect directly to the DRAM chips to minimize latency. Additionally, the module features eight dedicated ECC byte lanes (CB0-CB7) to support the 72-bit wide data bus. An independent I2C bus (SCL and SDA pins) interfaces with the onboard Serial Presence Detect (SPD) EEPROM, allowing the host system to read the module's timing parameters, capacity, and manufacturing data during the Power-On Self-Test (POST) sequence.

Core Architectural Features

• Registering Clock Driver (RCD): Integrates a high-performance buffer for command, address, and control signals, enabling high-density memory channel configurations by minimizing electrical load on the host CPU.
• Advanced Power Management: Operates with a primary VDD of 1.2V and a dedicated VPP of 2.5V for wordline activation, eliminating internal charge pumps and significantly reducing active power consumption compared to previous generations.
• 1Rx4 Organization with ECC: Built with 4-bit wide DRAM components to support advanced Error-Correcting Code algorithms (such as SDDC/Chipkill), ensuring high reliability in mission-critical server environments.
• Pseudo-Open Drain (POD) I/O: Utilizes POD signaling for the data bus, which terminates to VDD and only consumes power when driving a low signal, improving signal integrity and thermal efficiency at high frequencies.
• 16-Bank Architecture: Features 4 bank groups with 4 banks per group, maximizing memory access concurrency and optimizing data throughput via shortened bank-group-to-bank-group timing parameters.

Specifications Parameter Table

HMA41GR7MFR8N-TF Equivalents, Cross Reference & Lifecycle

The HMA41GR7MFR8N-TF is a mature component within the DDR4 lifecycle. While 2133 MT/s was the introductory speed for DDR4 server platforms (such as Intel Xeon E5 v3 series), it remains widely utilized in legacy hardware maintenance and specific embedded server applications. In modern deployments, it is often superseded by 2400 MT/s or 2666 MT/s modules, which are generally backward compatible and will downclock to 2133 MT/s if dictated by the memory controller.

Direct equivalents from other major DRAM manufacturers that share the exact 8GB, 1Rx4, PC4-2133P, RDIMM specifications include the Samsung M393A1G40DB0-CPB and the Micron MTA18ASF1G72PZ-2G1. When replacing or expanding memory in a server, it is critical to match the rank configuration (1Rx4) and module type (RDIMM) to prevent channel population errors or POST failures. Mixing RDIMMs with LRDIMMs or UDIMMs is strictly prohibited by JEDEC standards and Intel/AMD memory controller architectures. Hardware engineers and procurement specialists can Check HMA41GR7MFR8N-TF Inventory & Pricing to verify current availability and lifecycle status for maintenance operations.

Typical Applications & Circuit Considerations

The HMA41GR7MFR8N-TF is engineered for deployment in enterprise-grade hardware, including 1U/2U rackmount servers, blade servers, and high-end compute workstations. It is natively compatible with processor architectures such as the Intel Xeon E5-2600 v3 (Haswell-EP) and v4 (Broadwell-EP) families, as well as first-generation AMD EPYC (Naples) platforms. In these systems, the RDIMM architecture allows for up to 3 DIMMs per channel (3DPC) depending on the motherboard routing, enabling massive total system memory capacities required for virtualization, database caching, and high-performance computing (HPC).

From a PCB design and system integration perspective, routing a DDR4 memory channel requires strict adherence to impedance matching and trace length matching protocols. The data bus (DQ/DQS) is typically routed using a fly-by topology for the command, address, and clock signals, which reduces simultaneous switching noise (SSN) but introduces a timing skew. This skew is resolved during the memory training phase (write leveling) initiated by the CPU's memory controller at boot. Characteristic impedance targets are generally 40-50 ohms for single-ended traces and 85-100 ohms for differential pairs (such as the clock and DQS lines).

Power Delivery Network (PDN) design is also critical when integrating these modules. The motherboard must provide a highly stable 1.2V VDD supply capable of handling rapid transient load changes as the memory transitions from idle to active burst states. Adequate decoupling capacitance must be placed near the DIMM sockets to suppress high-frequency noise. Furthermore, thermal management is a vital consideration; the HMA41GR7MFR8N-TF includes a thermal sensor accessible via the I2C bus, allowing the system's Baseboard Management Controller (BMC) to monitor module temperatures and adjust chassis fan speeds accordingly to maintain the DRAM dies below their 85°C standard operating limit. For broader system designs requiring different capacities or speeds, engineers can Browse DDR4 Series to find the optimal memory configuration.

Video Demonstration

Frequently Asked Questions (HMA41GR7MFR8N-TF FAQ)

Q: What is the difference between the HMA41GR7MFR8N-TF RDIMM and a standard UDIMM?

A: The primary difference lies in the presence of a Registering Clock Driver (RCD) on the RDIMM. The RCD buffers the command, address, and clock signals coming from the memory controller before distributing them to the DRAM chips. This buffering reduces the electrical load on the CPU, allowing servers to support much higher memory capacities per channel, whereas UDIMMs lack this buffer and are limited in scalability.

Q: Can the HMA41GR7MFR8N-TF operate at lower frequencies if installed in an older system?

A: Yes, the module supports downward clocking and will automatically align with the maximum frequency supported by the host memory controller. During the POST sequence, the system reads the Serial Presence Detect (SPD) EEPROM and negotiates the appropriate timings, such as 1866 MT/s or 1600 MT/s. However, the module cannot exceed its maximum rated specification of 2133 MT/s.

Q: What is the purpose of the VPP voltage rail in this DDR4 module?

A: The VPP rail provides a dedicated 2.5V power supply specifically for the wordline activation within the internal DRAM architecture. By separating this high-voltage requirement from the primary core voltage, the main VDD rail can operate at a highly efficient 1.2V. This architectural change eliminates the need for inefficient internal charge pumps, significantly reducing the module's overall power consumption and heat generation.

Q: Is the HMA41GR7MFR8N-TF compatible with non-ECC desktop motherboards?

A: Generally, this module is not compatible with standard consumer desktop motherboards. Because it is a Registered DIMM (RDIMM), it requires a memory controller with specific microcode and hardware support to interface with the onboard RCD. Installing an RDIMM into a standard desktop motherboard that only supports Unbuffered DIMMs (UDIMMs) will typically result in a system POST failure.

Q: How does the 1Rx4 organization impact memory channel performance?

A: The 1Rx4 designation indicates a single-rank module built using DRAM chips with a 4-bit data width. This requires 18 individual DRAM chips to populate the 72-bit bus (64-bit data plus 8-bit ECC). Single-rank modules present a lower capacitive load to the memory channel compared to dual-rank or quad-rank modules, which often allows system integrators to populate more DIMMs per channel while maintaining higher data transfer rates.

Alan Carter

Senior Hardware Engineer & Component Specialist

Alan has over 15 years of expertise in embedded systems design, FPGA architecture, and global semiconductor supply chains. He specializes in component cross-referencing, lifecycle management, and helping OEMs navigate supply shortages.