What the decoder reads, and what it works out
A memory part number is a packed specification. Capacity, generation, module type, DRAM width and speed each sit at a fixed position. The decoder reads those positions using the manufacturer’s own numbering scheme, so it works on part numbers it has never seen, not only on a list of known ones.
Rank is the exception. Samsung, SK hynix and Micron’s DDR4 numbers do not print it, so the decoder works it out from capacity, die density and DRAM width and marks the result worked out. It agreed with the label on more than 100 modules from our buying catalog, but the label on the module has the final word. If the difference between 2Rx4 and 2Rx8 is new to you, read memory ranks explained.
Samsung part numbers
Samsung module numbers start with M3 (full-size DIMM) or M4 (SODIMM). The next two digits give the module type, and the letter after them gives the generation: A for DDR4, R for DDR5. The speed is the last two characters after the dash and the letter C.
Example: M393A4K40CB2-CTD is a 32GB DDR4-2666 RDIMM, 2Rx4 module.
| Characters | Field | Meaning |
|---|---|---|
| M | Product | Samsung memory module |
| 3 | Module format | DIMM |
| 93 | Module type | 288-pin registered DIMM, 72-bit (ECC) |
| A | DRAM type | DDR4 SDRAM (1.2V) |
| 4K | Depth | 4G words = 32GB module (built on 8Gb DRAM) |
| 4 | Banks & interface | 16 banks, POD 1.2V |
| 0 | DRAM width | x4 components |
| C | Component revision | C-die |
| B | Package | FBGA, flip chip (single die per package) |
| 2 | PCB revision | Revision 2 |
| C | Temperature & power | Commercial temperature (0–85°C), normal power |
| TD | Speed | DDR4-2666, CL19 |
Samsung module type codes
| Prefix | Generation | Module type |
|---|---|---|
| M393A | DDR4 | Registered DIMM (RDIMM) |
| M392A | DDR4 | Very-low-profile RDIMM |
| M386A | DDR4 | Load-reduced DIMM (LRDIMM) |
| M391A | DDR4 | ECC unbuffered DIMM |
| M378A | DDR4 | Unbuffered DIMM (desktop) |
| M471A | DDR4 | SODIMM (laptop) |
| M474A | DDR4 | ECC SODIMM |
| M321R | DDR5 | Registered DIMM (RDIMM) |
| M324R | DDR5 | ECC unbuffered DIMM |
| M323R | DDR5 | Unbuffered DIMM (desktop) |
| M425R | DDR5 | SODIMM (laptop) |
In the depth field, a K (as in 4K) means the module is built on 8Gb DRAM; a G means 4Gb or 16Gb DRAM, which the component revision letter settles. The digit after it gives the DRAM width: 0 is x4, 3 is x8.
SK hynix part numbers
SK hynix uses two formats. DDR4 modules mostly use the older one, which starts HMA followed by the DRAM density and depth. All DDR5 modules, and some later DDR4 ones, use a 15-character format that starts HMC (DDR5) or HMA (DDR4) followed by G or T and a capacity code.
DDR4 format
Example: HMA84GR7CJR4N-VK is a 32GB DDR4-2666 RDIMM, 2Rx4 module.
| Characters | Field | Meaning |
|---|---|---|
| HM | Product | SK hynix memory module |
| A | DRAM type | DDR4 SDRAM |
| 8 | Component density | 8Gb per DRAM package |
| 4G | Depth | 4G words = 32GB module |
| R | Module type | 288-pin registered DIMM |
| 7 | Data width & height | 72-bit (ECC), standard height |
| C | Die generation | C-die (4th generation) |
| J | Package | Flip-chip, single die |
| R | Package material | Lead-free and halogen-free (RoHS) |
| 4 | DRAM width | x4 components |
| N | Temperature & voltage | Commercial temperature (0–85°C), 1.2V |
| VK | Speed | DDR4-2666, CL19 |
15-character format (DDR5)
Example: HMCG88MEBRA107N is a 32GB DDR5-4800 RDIMM, 2Rx8 module.
| Characters | Field | Meaning |
|---|---|---|
| HM | Product | SK hynix memory module |
| C | DRAM type | DDR5 SDRAM |
| G8 | Module density | 32GB |
| 8 | DRAM width | x8 components |
| M | Die generation | M-die (1st generation) |
| EB | Speed | DDR5-4800, CL40 |
| R | Module type | RDIMM |
| A | Die density & build | 16Gb DRAM, low profile, commercial temperature |
| 107 | Package & module options | Identifies the register (RCD) and power-management IC combination |
| N | Sales type | Normal |
| Code | Capacity | Code | Capacity |
|---|---|---|---|
| G6 | 8GB | G9 | 64GB |
| G7 | 16GB | GM | 96GB |
| GJ | 24GB | T0 | 128GB |
| G8 | 32GB | T1 | 256GB |
| GY | 48GB | T2 | 512GB |
Micron part numbers
Micron DDR4 modules start MTA and DDR5 modules start MTC. Both open with the number of DRAM die on the module. The DDR4 scheme leaves rank and DRAM width to be worked out from that die count; the DDR5 scheme prints both.
DDR4 format
Example: MTA36ASF4G72PZ-2G6D1 is a 32GB DDR4-2666 RDIMM, 2Rx4 module.
| Characters | Field | Meaning |
|---|---|---|
| MT | Product | Micron Technology |
| A | DRAM type | DDR4 SDRAM |
| 36 | Number of DRAM die | 36 |
| A | Voltage | 1.2V |
| SF | Module options | FBGA with temperature sensor |
| 4G | Depth | 4G words = 32GB module |
| 72 | Module width | 72-bit (ECC) |
| P | Module type | 288-pin registered DIMM |
| Z | Package code | Commercial temperature, halogen-free |
| -2G6 | Speed | DDR4-2666, CL19 |
| D | Die revision | Revision D |
| 1 | PCB revision | Revision 1 |
The letters after the 72 or 64 give the module type: P is RDIMM, L is LRDIMM, A is UDIMM and H is SODIMM. A package code of DZ rather than Z marks the dual-rank build, which is how an 18-die 16GB module is told apart: PZ is 1Rx4, PDZ is 2Rx8.
DDR5 format
Example: MTC40F2046S1RC56BD1 is a 64GB DDR5-5600 RDIMM, 2Rx4 module.
| Characters | Field | Meaning |
|---|---|---|
| MT | Product | Micron Technology |
| C | DRAM type | DDR5 SDRAM |
| 40 | Number of DRAM die | 40 |
| F | Module power input | 12V (server RDIMM class) |
| 2 | Ranks | 2 ranks |
| 0 | Logical ranks | No 3DS stacking |
| 4 | DRAM width | x4 components |
| 6 | Module density | 64GB |
| S | Module height | Standard height (low profile) |
| 1 | Die package | Single die per package |
| R | Module type | Registered DIMM |
| C | Temperature | Commercial temperature |
| 56B | Speed | DDR5-5600, CL46 |
| D | Die revision | Revision D |
| 1 | PCB revision | Revision 1 |
| Density code | Capacity | Type code | Module type |
|---|---|---|---|
| 3 | 8GB | R | RDIMM |
| 4 | 16GB | E | ECC UDIMM |
| Y | 24GB | U | UDIMM |
| 5 | 32GB | S | SODIMM |
| X | 48GB | T | ECC SODIMM |
| 6 | 64GB | H | MRDIMM |
| W | 96GB | ||
| 7 | 128GB |
Kingston part numbers
Kingston’s Server Premier (KSM) and ValueRAM (KVR) numbers are the most readable of the four: speed, module type, rank, DRAM width and capacity are all printed, and Server Premier adds the DRAM manufacturer and die revision. Kingston’s system-specific numbers (KTD-, KTH-, KTL-) are shorter and name the server family the module was built for.
Example: KSM56R46BD4PMI-64HAI is a 64GB DDR5-5600 RDIMM, 2Rx4 module.
| Characters | Field | Meaning |
|---|---|---|
| KSM | Product line | Kingston Server Premier |
| 56 | Speed | DDR5-5600 |
| R | Module type | ECC registered DIMM (EC8, x80) |
| 46B | CAS latency | CL46-45-45 |
| D | Ranks | Dual rank |
| 4 | DRAM width | x4 components |
| P | Power-management IC (PMIC) | MPS |
| M | SPD hub | Montage |
| I | Thermal sensor | Renesas |
| 64 | Capacity | 64GB |
| H | DRAM manufacturer | SK hynix |
| A | Die revision | A-die |
| I | Register (RCD) | Renesas |
Speed codes at a glance
Each manufacturer has its own code for the same speed. The same two letters can mean different things: WM is DDR5-5600 on a Samsung module and DDR4-2933 on an SK hynix one.
| Speed | Label | Samsung | SK hynix | Micron |
|---|---|---|---|---|
| DDR4-2133 | PC4-17000 | PB | TF | -2G1 |
| DDR4-2400 | PC4-19200 | RC | UH | -2G3 |
| DDR4-2666 | PC4-21300 | TD | VK | -2G6 |
| DDR4-2933 | PC4-23400 | VF | WM | -2G9 |
| DDR4-3200 | PC4-25600 | WE | XN | -3G2 |
| DDR5-4800 | PC5-38400 | QK | EB | 48B |
| DDR5-5600 | PC5-44800 | WM | GB | 56B |
| DDR5-6400 | PC5-51200 | CP | HB | 64B |
Sources and accuracy
The decoding rules are based on the manufacturers’ published part-numbering documentation: Samsung’s DDR4 product guide and DDR5 module datasheets, SK hynix’s DDR4 and DDR5 module part-number decoders, Micron’s module part numbering guides and Kingston’s memory part number decoder. They were then checked against real modules from our buying catalog.
Manufacturers add codes over time. When the decoder meets a code it does not know, it says so instead of guessing. If it gets a part number wrong, email harlan@ocitech.com and we will fix it.
