The HMA42GR7AFR4N-TF is a high-density, high-performance 16GB DDR4 Registered DIMM (RDIMM) manufactured by SK Hynix. It is specifically engineered to solve the memory capacity and reliability challenges inherent in enterprise-level computing environments. By incorporating features like a Registering Clock Driver (RCD) and Error-Correcting Code (ECC), this module provides the stability and data integrity required for servers, data centers, and high-performance workstations that cannot tolerate data corruption or downtime.
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What is the HMA42GR7AFR4N-TF?
The SK Hynix HMA42GR7AFR4N-TF is a 16GB (Gigabyte) DDR4 SDRAM memory module designed for the server and enterprise market. To understand its role, it's useful to decode its part number. 'H' stands for Hynix, 'M' for Module, 'A' for DDR4 SDRAM, '4' for the 1.2V operating voltage, '2G' for the 16GB capacity, 'R' for Registered DIMM, '7' for the x4 DRAM organization, and '-TF' indicating the DDR4-2133 speed grade. This module is not intended for consumer desktops or laptops but is a cornerstone component for building robust server infrastructure.
At its core, this is a JEDEC-compliant 288-pin DDR4 memory module. The "Registered" (RDIMM) designation is its most critical feature for server applications. Unlike unbuffered DIMMs (UDIMMs) used in consumer PCs, an RDIMM includes a Registering Clock Driver (RCD) chip mounted on the module itself. This RCD acts as a buffer for all address, command, and clock signals traveling from the CPU's memory controller to the DRAM chips. By buffering these signals, the RCD reduces the electrical load on the controller. This fundamental design choice allows a single memory channel to support a greater number of memory modules, enabling the massive memory capacities (often multiple terabytes) required by modern servers for virtualization, in-memory databases, and large-scale data analytics.
Furthermore, the HMA42GR7AFR4N-TF is an ECC (Error-Correcting Code) module. It features a 72-bit wide data bus, compared to the 64-bit bus on non-ECC memory. The extra 8 bits are used to store parity information generated by the memory controller. This allows the system to detect and correct single-bit errors in real-time, and detect multi-bit errors. In a server environment running 24/7, where cosmic rays or other electrical noise can flip a bit, this capability is not a luxury—it is a requirement to prevent data corruption, application crashes, and system instability. The combination of the registered design for scalability and ECC for reliability makes this module a workhorse for mission-critical systems.
Pinout Configuration and Packaging
The HMA42GR7AFR4N-TF is built on the industry-standard 288-pin DDR4 DIMM form factor. This physical standard, defined by JEDEC, ensures interoperability between different module manufacturers and server platforms. The 288-pin connector provides the necessary I/O for the high-speed data transfer, power, and control signals. A key physical characteristic of the DDR4 standard is the curved edge connector, designed to ease insertion, and a specific notch location that is different from DDR3 modules to physically prevent accidental installation in an incompatible socket.
While a full pin-by-pin list is impractical and unnecessary for system-level design, understanding the key pin groups is crucial for any hardware engineer working with these modules:
- Power Pins (VDD, VSS, VPP, VREFCA): DDR4 introduced a lower main operating voltage of 1.2V (VDD) to reduce power consumption. A separate 2.5V rail (VPP) is also required for word line boosting, a technique to improve signal margins within the DRAM cells. VSS provides the ground reference, and VREFCA provides a stable reference voltage for the command/address bus receivers.
- Data Bus (DQ0-DQ63) & ECC Bus (CB0-CB7): This constitutes the 72-bit parallel interface for data transfer. 64 bits are for the actual data, and 8 bits are for the ECC check bits.
- Data Strobe (DQS_t/DQS_c): These are differential signal pairs that accompany the data signals, acting as a clock to latch the data at the receiver, ensuring reliable capture at high speeds.
- Address & Command Bus (A0-A17, BA0-BA1, BG0-BG1): These pins carry memory addresses and commands (like read, write, activate). On an RDIMM like the HMA42GR7AFR4N-TF, these signals are intercepted and re-driven by the onboard RCD.
- Control and Clock (CK_t/CK_c, CKE, CS_n, ODT): These include the main differential system clock, Clock Enable, Chip Select (for selecting specific ranks), and On-Die Termination control signals.
The individual DRAM components on the module are packaged in a Fine-Pitch Ball Grid Array (FBGA), which allows for a high-density of connections in a small footprint, essential for achieving the module's 16GB capacity.
Core Architectural Features
- On-Board Registering Clock Driver (RCD): The module integrates a dedicated RCD chip (e.g., a JEDEC-standard SSTE32882). This component buffers the command, address, and clock signals, presenting a single, clean electrical load to the memory controller. This significantly improves signal integrity, enabling stable operation with more DIMMs per channel and thus higher total system memory.
- Integrated ECC Functionality: With a 72-bit data path (organized as 2Gx72), the module fully supports Error-Correcting Code. It can detect and correct any single-bit memory error on-the-fly. This is non-negotiable for applications in finance, scientific computing, and enterprise databases where data integrity is paramount.
- Dual-Rank, x4 Organization (2Rx4): This module is configured as a dual-rank (2R) device. This means it has two independent sets of DRAM chips that can be accessed by the memory controller, which can improve performance through rank interleaving. The x4 organization indicates that each individual DRAM chip on the module has a 4-bit wide data bus. This organization is often preferred in servers for its ability to correct more types of memory errors (Chipkill/SDDC).
- DDR4-2133P Speed and Timings: This module is rated for a data transfer rate of 2133 MT/s (MegaTransfers per second), which corresponds to a PC4-17000 rating. At this speed, it operates with a standard CAS Latency (CL) of 15, a tRCD of 15, and a tRP of 15, as defined by JEDEC for the 'P' speed bin. This provides a balance of throughput and latency suitable for a wide range of server workloads.
- On-Die Termination (ODT) and Vref Training: The HMA42GR7AFR4N-TF incorporates dynamic On-Die Termination. The DRAM chips themselves contain termination resistors that can be enabled or disabled to match the impedance of the signal lines, minimizing signal reflections that can cause errors at high frequencies. The module also supports Vref training sequences, allowing the memory controller to fine-tune the reference voltages for optimal signal reception.
Specifications Parameter Table
| Specification | Technical Details |
|---|---|
| Module Type | DDR4 Registered DIMM (RDIMM) with ECC |
| Density | 16GB |
| Organization | 2048M x 72-bit (Dual Rank, x4-based) |
| Speed Grade | DDR4-2133P / PC4-17000 |
| CAS Latency (CL) | 15 (at a clock cycle of 1066.7 MHz) |
| Operating Voltage (VDD) | 1.2V (±0.06V) |
| Pin Count | 288-pin |
| Operating Temperature (TCASE) | 0°C to 95°C |
| Module Height | Standard 31.25mm |
HMA42GR7AFR4N-TF Equivalents, Cross Reference & Lifecycle
The HMA42GR7AFR4N-TF is a mature DDR4 product. While the industry is transitioning to DDR5 for the latest generation of servers, DDR4 remains the standard for a vast installed base of enterprise hardware, including systems based on Intel Xeon Scalable (1st/2nd Gen) and AMD EPYC (1st/2nd Gen) processors. This module is in active production and widely available for system upgrades and maintenance. However, for new ground-up designs, engineers should consult their CPU and motherboard vendor's roadmaps.
When seeking alternatives or replacements, it is critical to match the key specifications: Type (RDIMM), Capacity (16GB), Rank (2R), Organization (x4), and Speed (2133). Using modules with mismatched specifications can lead to boot failures, instability, or the entire memory bus defaulting to the slowest common denominator. Potential pin-compatible and functionally equivalent parts from other major manufacturers include:
- Samsung: M393A2G40DB0-CPB
- Micron: MTA18ASF2G72PDZ-2G1B2
Always verify compatibility by consulting the server or motherboard's official Qualified Vendor List (QVL) before purchasing. The QVL is the definitive source for validated memory configurations. For availability of this specific module, you can Check HMA42GR7AFR4N-TF Inventory & Pricing.
Typical Applications & Circuit Considerations
The HMA42GR7AFR4N-TF is exclusively designed for high-reliability, high-availability computing platforms. You will find this module and its equivalents in the following systems:
- Enterprise Rack and Blade Servers: The backbone of modern data centers, used for web hosting, application serving, and database management.
- Virtualization Hosts: Servers running hypervisors like VMware vSphere, Microsoft Hyper-V, or KVM, where high memory capacity is essential to support numerous virtual machines.
- Cloud Computing Infrastructure: The physical servers that power public and private cloud services.
- High-Performance Computing (HPC) Clusters: Systems used for scientific research, financial modeling, and complex simulations that require both large memory sets and data integrity.
- Network Attached Storage (NAS) and Storage Area Network (SAN) Appliances: High-end storage systems that often use large DRAM caches to accelerate I/O performance.
From a hardware design and integration perspective, several considerations are paramount when working with DDR4 RDIMMs like this one. The power delivery network (PDN) must be robust, providing clean 1.2V (VDD) and 2.5V (VPP) rails with minimal ripple and noise. This requires careful placement of bulk and decoupling capacitors very close to the DIMM sockets on the motherboard. PCB layout is another critical area. The high-speed data lines (running at over 1 GHz) demand controlled impedance traces (typically 40-50 Ω single-ended) and precise length-matching within data byte lanes and between data and strobe signals to avoid timing skew. Any failure here will result in data integrity issues that are difficult to debug.
Thermal management is also a significant concern. A server chassis fully populated with memory modules can generate a substantial amount of heat. The HMA42GR7AFR4N-TF includes an on-board thermal sensor that communicates over the SMBus interface. The system's Baseboard Management Controller (BMC) must monitor this sensor to dynamically adjust cooling fan speeds, ensuring the module's case temperature remains within the specified 0°C to 95°C operating range. Failure to provide adequate airflow can lead to thermal throttling or premature component failure. For engineers working with these components, it's essential to explore the broader ecosystem of memory technologies. You can Browse DDR4 Series to see a wider range of options.
Video Demonstration
Frequently Asked Questions (HMA42GR7AFR4N-TF FAQ)
Is the HMA42GR7AFR4N-TF compatible with my desktop PC?
No, this memory module is not compatible with standard consumer desktop or laptop computers. The HMA42GR7AFR4N-TF is a Registered DIMM (RDIMM) with ECC. Consumer motherboards and processors almost exclusively support Unbuffered DIMMs (UDIMMs). The physical pinout and electrical signaling are different, and a desktop system's BIOS and memory controller will not be able to initialize or communicate with an RDIMM.
What does "2Rx4" mean in the module's specification?
"2Rx4" refers to the module's rank and the organization of the DRAM chips. "2R" means it is a dual-rank module, containing two independent, selectable sets of DRAMs that share the same data bus. "x4" (read as "by four") means that each individual DRAM chip on the module has a 4-bit wide data interface. This combination is common in servers as it allows for advanced ECC schemes like "Chipkill" or Single Device Data Correction (SDDC), which can correct for the failure of an entire DRAM chip.
Can I mix HMA42GR7AFR4N-TF with faster DDR4 modules in my server?
While technically possible in some systems, it is strongly discouraged. If you mix modules of different speeds, the server's memory controller will force all modules to operate at the speed of the slowest installed DIMM. In this case, if you installed a DDR4-2666 module alongside this DDR4-2133 module, both would run at 2133 MT/s, negating the benefit of the faster module. For optimal stability and performance, it is best practice to populate all memory channels with identical modules.
What is the difference between an RDIMM and an LRDIMM?
Both RDIMMs (Registered DIMMs) and LRDIMMs (Load-Reduced DIMMs) are used in servers to increase memory capacity. An RDIMM, like the HMA42GR7AFR4N-TF, has a Registering Clock Driver (RCD) that buffers the command, address, and clock signals. An LRDIMM goes a step further by also including a Data Buffer (DB) chip on the module. This DB buffers the actual DQ data signals, further reducing the electrical load on the memory controller and allowing for even higher capacity configurations, though often with a slight increase in latency.
How do I verify if this module is compatible with my server?
The most reliable method is to consult your server's official documentation, specifically the technical specifications or service manual. Manufacturers like Dell, HPE, and Lenovo publish a Qualified Vendor List (QVL) for each server model. This list contains the exact part numbers of the memory modules that have been tested and validated for that specific platform. Cross-referencing the HMA42GR7AFR4N-TF or its direct equivalents against your server's QVL is the best way to guarantee compatibility.
