RDIMM (Registered DIMM):

This is the standard memory type for servers and workstations. It incorporates a register (located between the memory controller and the DRAM chips) that buffers address and control signals, enabling support for more memory modules (DIMMs) on a single memory channel.

Advantages: Higher stability, reliability, and support for larger memory configurations.

Disadvantages: Slightly higher latency (typically one extra clock cycle) compared to UDIMM (Unbuffered), but this is negligible under server workloads. The stability and capacity advantages are decisive.

Capacity & Speed:

• 64GB is a high-capacity option for a single module in the DDR4 era, making it highly suitable for applications requiring large memory, such as virtualization, large databases, in-memory analytics, and high-performance computing (HPC).

• 3200 MT/s is a high-frequency specification for later DDR4 generations, offering excellent bandwidth. Note: Whether it can run at 3200 MT/s on your server depends on the CPU, motherboard, and memory configuration.

Model Number Decoding:

• M393: Samsung’s server memory series.

• A8G40: “A8G” indicates a 64GB capacity. “40” likely represents chip organization or a design revision.

• BB4: Indicates DDR4.

• -CWE: The critical suffix! “C” often indicates a 4th internal version or revision. The “WE” combination denotes its speed, latency (timings), and other parameters.

• The specific meaning of -CWE is: DDR4-3200, CL22, 1.2V, utilizing x4-width chips.

Compatibility & Important Usage Notes

Server Compatibility:

Although the model name includes “for SAMSUNG Servers,” it is not exclusive to Samsung-branded servers. It complies with JEDEC standards and can be used in any server platform supporting DDR4 RDIMMs and 64GB single-module capacity.

Primary Compatible Platforms: Intel Xeon Scalable processor families (e.g., Cascade Lake, Ice Lake, and some Cooper Lake and Skylake SP/AP platforms) and AMD EPYC 7002/7003 series (Rome, Milan) platforms.

Always check your server/motherboard’s official compatibility list (QVL): Before purchasing, visit the official website of your server brand (e.g., Dell, HPE, Lenovo, Supermicro) and consult the memory support list for your specific model (e.g., Dell PowerEdge R740, HPE ProLiant DL380 Gen10). Confirm that M393A8G40BB4-CWE or a specific variant is listed. This is the most reliable way to avoid compatibility issues.

Mixing Modules:

• It is strongly recommended to use memory modules with identical model, capacity, speed, and timings in the same server.

• If mixing is necessary, ensure at minimum the same type (RDIMM), capacity, and speed, and install them in corresponding slots within the same channel. Mixing may cause the system to run at a reduced speed (e.g., down to 2933 or 2666 MT/s) or become unstable.

Channels & Installation:

• For optimal performance, memory should be installed in pairs or as specified by the motherboard manual (e.g., install the same number and specification of DIMMs per channel for each CPU).

• Typically, fill the memory channels for CPU1 first before installing modules for CPU2.

Purchasing & Authenticity Verification

Source: It is advisable to purchase from reputable server component distributors or official channels.

Second-hand Market: This model is commonly available on the secondary market (e.g., eBay, Taobao) at relatively advantageous prices compared to new stock, but caution is required.

Authenticity Verification:

• Label: Check the print quality, font, and serial number on the Samsung label for clarity.

• Chips: The memory chips should have the Samsung logo and consistent model codes.

• SPD Information: Use tools like CPU-Z within the system to read SPD information. Verify that the manufacturer, model, speed, and timings match the label.

Summary

M393A8G40BB4-CWE is a high-performance 64GB DDR4-3200 RDIMM server memory module, well-suited for enterprise applications requiring large capacity and high bandwidth.

The Most Important Step Before Proceeding:

Cross-reference your server model and motherboard manual, and check the official memory compatibility list (QVL) to confirm this part is explicitly supported. This is crucial for ensuring system stability.