SK hynix Memory Guide: Part Numbers, Speed Codes & Compatible Modules
SK hynix memory part numbers encode the module specification: DDR generation, capacity, module type, DRAM width and speed. This guide shows how to read them, so you can match a module from a server label, a BMC inventory or a quote. To go straight to the products, shop SK hynix part number cross-reference memory or type the part number into the search bar at the top of the page.
Generation prefixes
| Prefix | Generation | Module types on this page |
|---|---|---|
| HMT | DDR3 | RDIMM, LRDIMM, ECC UDIMM, UDIMM, SODIMM |
| HMA | DDR4 | RDIMM, VLP RDIMM, LRDIMM, ECC UDIMM, UDIMM, ECC SODIMM, SODIMM |
| HMAG, HMAT | DDR4, later numbering | RDIMM, LRDIMM (HMAT: 128GB and 256GB) |
| HMCG | DDR5 | RDIMM, ECC UDIMM, UDIMM, SODIMM |
| HMCT | DDR5, 3DS stacked | 128GB and 256GB RDIMM |
The structure of a DDR4 part number
Take HMA84GR7CJR4N-XN. HMA is DDR4. 8 is the DRAM die density: 4 is 4Gb, 8 is 8Gb and A is 16Gb. 4G is the capacity (32GB). R7 is the module type (RDIMM). CJ is the die revision. R4 is the DRAM width: R4 is x4, R8 is x8 and R6 is x16. N is a package code. -XN is the speed (DDR4-3200). DDR3 numbers follow the same layout with the HMT prefix, for example HMT42GR7AFR4C-RD, a 16GB DDR3-1866 RDIMM.
Module type codes
| Type code (DDR3, DDR4) | Module |
|---|---|
| R7 | ECC Registered (RDIMM) |
| R8 | ECC Registered, very low profile (VLP RDIMM) |
| L7 | ECC Load-Reduced (LRDIMM) |
| U7 | ECC Unbuffered (ECC UDIMM) |
| U6 | Non-ECC Unbuffered (UDIMM) |
| S7 | ECC SODIMM |
| S6 | Non-ECC SODIMM |
Speed suffixes
| DDR4 suffix | Speed | DDR3 suffix | Speed |
|---|---|---|---|
| -TF | DDR4-2133 | -G7 | DDR3-1066 |
| -UH, -UL | DDR4-2400 | -H9 | DDR3-1333 |
| -VK, -VN, -VJ | DDR4-2666 | -PB | DDR3-1600 |
| -WM, -WR | DDR4-2933 | -RD | DDR3-1866 |
| -XN, -XS | DDR4-3200 |
On DDR3 the letter just before the dash gives the voltage: C is 1.5V and A is a 1.35V low-voltage (DDR3L) part.
DDR4 capacity codes
| Capacity code (after HMA and the density character) | Capacity | Example part | Module |
|---|---|---|---|
| 51 | 4GB | HMA851S6CJR6N-VK | 4GB 1Rx16 SODIMM, DDR4-2666 |
| 1G | 8GB | HMA81GR7CJR8N-XN | 8GB 1Rx8 RDIMM, DDR4-3200 |
| 2G | 16GB | HMA82GR7CJR8N-XN | 16GB 2Rx8 RDIMM, DDR4-3200 |
| 4G | 32GB | HMA84GR7CJR4N-XN | 32GB 2Rx4 RDIMM, DDR4-3200 |
| 8G | 64GB | HMAA8GR7AJR4N-XN | 64GB 2Rx4 RDIMM, DDR4-3200 |
| AG | 128GB | HMABAGL7ABR4N-XN | 128GB 4Rx4 LRDIMM, DDR4-3200 |
How capacity, density and width set the rank
The same capacity can be built more than one way, and the rank changes with it. Read the density character and the width code together:
| Part | Die density | Width | Module |
|---|---|---|---|
| HMA84GR7CJR4N-XN | 8 (8Gb) | R4 (x4) | 32GB 2Rx4 |
| HMAA4GR7CJR4N-XN | A (16Gb) | R4 (x4) | 32GB 1Rx4 |
| HMAA4GR7CJR8N-XN | A (16Gb) | R8 (x8) | 32GB 2Rx8 |
These three are different modules to the server. When adding to a populated system, match the rank and width of what is installed.
Later DDR4 numbers: HMAG and HMAT
SK hynix's later DDR4 parts use a shorter layout, close to DDR5: the prefix, a two-character capacity and organization code, the die revision, then the module type near the end (R for RDIMM, L for LRDIMM). HMAT marks the high-capacity modules. The parts on this page are DDR4-3200. Distributors and server makers often add a three-digit code and N to the end, as in HMAG78EXNRA084N; the module is the same.
| Code | Module | Example part |
|---|---|---|
| HMAG78 | 16GB 2Rx8 RDIMM | HMAG78EXNRA |
| HMAG84 | 32GB 1Rx4 RDIMM | HMAG84DXNRB |
| HMAG88 | 32GB 2Rx8 RDIMM | HMAG88DXNRB |
| HMAG94 | 64GB 2Rx4 RDIMM | HMAG94DXNRB |
| HMAT04 | 128GB 4Rx4 LRDIMM | HMAT04DXNLB |
| HMAT14 | 256GB 8Rx4 RDIMM or LRDIMM | HMAT14JXSRB120N |
DDR5 part numbers
DDR5 numbers start with HMCG for standard modules and HMCT for 3DS stacked modules. The two characters after the prefix give capacity and organization. Take HMCG94AGBRA: 94 is 64GB 2Rx4, G is DDR5-5600 and R is RDIMM.
| Code | Module | Example part |
|---|---|---|
| HMCG66 | 8GB 1Rx16 | HMCG66AEBUA |
| HMCG78 | 16GB 1Rx8 | HMCG78AGBRA |
| HMCG84 | 32GB 1Rx4 | HMCG84AGBRA |
| HMCG88 | 32GB 2Rx8 | HMCG88AGBRA |
| HMCGY8 | 48GB 2Rx8 | HMCGY8MGBEB |
| HMCG94 | 64GB 2Rx4 | HMCG94AGBRA |
| HMCGM4 | 96GB 2Rx4 | HMCGM4MGBRB |
| HMCT04 | 128GB 3DS (4Rx4; HMCT04MHBRC at DDR5-6400 is 2Rx4) | HMCT04AGERA |
| HMCT14 | 256GB 8Rx4 3DS | HMCT14AGERA |
| Position | Code | Meaning |
|---|---|---|
| Letter after the capacity code (8th character) | E · G · H | DDR5-4800 · DDR5-5600 · DDR5-6400 |
| 10th character | R or Q · E · U · S | RDIMM · ECC UDIMM · non-ECC UDIMM · SODIMM |
| Trailing digits and N (e.g. 195N) | — | build variant; the module specification is set by the characters before it |
Where you will find the number
- On the module label. Server makers including Dell, HPE, Lenovo, Cisco and Supermicro often ship SK hynix modules; the SK hynix number usually appears on the label beside or under the server maker's own part number.
- In the BMC inventory (iDRAC, iLO, XClarity, CIMC or IPMI). A slot holding an SK hynix module lists its SK hynix part number.
- In a board's qualified memory list. Motherboard and server makers often list SK hynix numbers directly.
- In a quote or configurator bill of materials. Resellers often quote SK hynix numbers.
What a compatible module is
The cross-reference collection lists NEMIX RAM modules matched to each SK hynix number on every attribute the memory controller reads: generation, capacity, ECC, buffering, speed, rank and width, voltage and pin count. Every module is researched, matched, and compatibility-tested by NEMIX RAM, a US-based server memory specialist since 1993, and backed by a lifetime warranty.
Shop by module type
- DDR5 RDIMM and DDR4 RDIMM for servers
- DDR4 LRDIMM for high-capacity servers
- ECC UDIMM for entry servers and workstations
- ECC SODIMM for NAS and edge systems
Other memory makers: the Samsung memory part number guide and Micron part number cross-reference.
Buying for a fleet
Purchase orders, net terms and volume pricing are available for data centers, research labs, universities, government buyers and resellers. Send SK hynix part numbers with quantities, or a BMC inventory export, and we will return a matched set. Request a quote.
Frequently asked
My part number is not listed.
Check the capacity code, type, width and speed against the tables above; a listing that matches all of them is the same module. If nothing matches, send us the number and we will confirm the right module.
My module is -VK but the server supports DDR4-2933.
-VK is DDR4-2666 and runs at 2666. A -WM (2933) or -XN (3200) module runs at the speed the processor and population support, so a faster module is a safe upgrade.
Can RDIMM and LRDIMM be mixed?
No. R7 (RDIMM) and L7 (LRDIMM) modules cannot be installed in the same server.
Is a DDR5 RDIMM with Q in the 10th position different from R?
Both are RDIMMs. Match the capacity code and speed letter as listed.
NEMIX RAM can deliver any Configuration your Fleet Requires
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