SK hynix RAM 8GB and 16GB: How to Buy the Right Server Memory

SK hynix is one of the major DRAM manufacturers, and its server modules are widely used by server OEMs. That makes SK hynix RAM a common replacement and upgrade part, and it is why buyers ask where to find it cheaply. The honest answer is that the right part number matters more than the listing price. This guide lists the 8GB and 16GB SK hynix modules we carry, explains how to match generation, speed, rank and voltage to your server, and covers the mixing rules that decide whether an upgrade works.

Which SK hynix 8GB and 16GB modules are available?

• 8GB DDR4-3200 RDIMM: PC4-25600, CL22, 1.2V, dual rank (2Rx4), 288-pin.
• 8GB DDR4-2933 RDIMM: PC4-23400, CL21, 1.2V, 2Rx4, 288-pin.
• 8GB DDR4-2666 RDIMM: PC4-21300, CL19, 1.2V, 2Rx4, 288-pin.
• 8GB DDR4-2400 RDIMM: PC4-19200, CL17, 1.2V, 2Rx4, 288-pin.
• 8GB DDR3-1600 RDIMM: PC3-12800, CL11, 1.35V, 2Rx4, 240-pin, for older DDR3 servers.
• 8GB DDR5-5600 UDIMM (part number HMCG66AGBUA084N): an unbuffered module for platforms that specify UDIMMs, not a drop-in for RDIMM servers.
• 16GB DDR5-4800 RDIMM: PC5-38400, CL40, 1.1V, dual rank (2Rx8), 288-pin.

You can filter the full range by 8GB or 16GB. One caution when searching by capacity: the memory category also lists bare SK hynix DRAM components, single chips used in board-level manufacturing and repair. Those are not DIMMs. If a listing says "DRAM memory chip" rather than RDIMM, LRDIMM or UDIMM, it is not the part for a server slot.

DDR4 or DDR5: which does your server take?

The CPU platform decides. As a rule of thumb, first-generation Intel Xeon Scalable servers run DDR4-2666, second-generation Xeon Scalable runs DDR4-2933, and third-generation Xeon Scalable and AMD EPYC 7002/7003 systems run DDR4-3200. 4th Gen Xeon Scalable and AMD EPYC 9004 moved to DDR5-4800, and 5th Gen Xeon Scalable supports DDR5-5600. Your server vendor's memory configuration guide is the final word.

DDR4 and DDR5 modules both have 288 pins, but the key notch sits in a different position, so a DDR5 module cannot seat in a DDR4 slot. DDR5 also moves power regulation onto the module and splits each DIMM into two independent subchannels, so the generations are not electrically compatible either. DDR3 server modules are a separate 240-pin standard.

How do you match speed, rank and voltage to the server?

• Speed: buy the grade your platform runs. A faster module works in a slower platform at the platform's speed (DDR5-5600 in a DDR5-4800 server runs at 4800 MT/s), so you pay for speed you cannot use unless the faster part is the qualified one. Two DIMMs per channel often lowers the supported speed further.
• Rank and chip width: 2Rx4 means two ranks built from 4-bit-wide DRAM chips; 2Rx8 uses 8-bit-wide chips. On many server platforms x4 modules support the stronger chip-level ECC modes, and rank count affects how many modules a channel can take. Match what the platform's memory guide specifies.
• Voltage: fixed by generation. DDR4 is 1.2V and DDR5 is 1.1V. DDR3 is the exception, with 1.5V standard modules and 1.35V low-voltage modules such as the 8GB DDR3-1600, so check which the server supports.
• Module type: RDIMM, LRDIMM and UDIMM are different products. Most two-socket servers take RDIMMs; LRDIMMs such as the 128GB DDR4-3200 LRDIMM (4Rx4 3DS) exist for maximum capacity; UDIMMs belong in entry servers and workstations that specify them.
• CAS latency: the server sets timings from the module's SPD data, and CL follows the speed grade. Do not shop by CL.

Can you mix SK hynix RAM with other modules?

• Never mix RDIMMs with LRDIMMs or UDIMMs in the same server.
• Mixed speeds work on most platforms, but every module runs at the slowest speed present.
• Mixed capacities are allowed on many platforms within strict population rules. Identical modules in every populated channel is the safe choice.
• On DDR5 platforms, many vendors do not allow x4 and x8 modules to be mixed, so a 2Rx8 16GB module and a 2Rx4 32GB module may not coexist.
• Different manufacturers with identical specifications usually work together, but OEM support may only cover the OEM's own part numbers. If the server is under support, match the qualified part.
• Populate channels evenly and balance memory across both CPUs. An unbalanced layout costs bandwidth even when total capacity looks right.

Where can I find the best deals on SK hynix RAM modules?

The best deal is the qualified part number for your platform, new, with warranty, bought as a matched set. What moves the price:

• Generation and speed grade. Current DDR5 grades are in active production; older DDR4 grades and DDR3 come from shrinking supply and can cost more than their age suggests.
• Capacity and density. High-capacity 3DS LRDIMMs carry a premium per module, while small modules can cost more per gigabyte.
• OEM part numbers. The same module sold under a server vendor's part number is often priced differently from the manufacturer part number.
• DRAM market cycles. Memory pricing moves with industry supply, so quotes are time-limited.
• Quantity. Buying every module for a server at once keeps the set identical.

Before asking for a quote, gather the details that pin down the exact part. It takes a few minutes and removes most of the guesswork:

• Server make and model, including generation (for example, the Gen or series suffix), and the installed CPU model.
• The part number printed on the label of an existing module, or as reported by the server's management controller or operating system inventory.
• How many slots are populated today, how many are free, and whether you plan one or two DIMMs per channel.
• The target capacity per server and whether the server is under an OEM support contract that requires OEM part numbers.

With that, Nexus Compute can quote the qualified SK hynix part and check it against your platform before dispatch. Current pricing is on each product page or quoted within 48 business hours, with purchase orders and net terms for qualified organizations.

What if 8GB or 16GB modules are too small?

Small modules fill slots quickly: an eight-channel DDR4 socket populated with 8GB RDIMMs holds 64GB, which is modest for virtualization or databases. Larger SK hynix options include the 64GB DDR4-3200 ECC RDIMM (HMAA8GR7AJR4N-XN), the 128GB DDR4-3200 LRDIMM, and 32GB DDR5 RDIMMs at DDR5-5600 (CL46), DDR5-6400 (CL52, 2Rx4) and DDR5-6800 (CL54, 2Rx4). The fastest grades only run at their rated speed on platforms that support them. When a server is short of memory, moving to fewer, larger modules is often the better path than filling every slot with 8GB parts, because it keeps one DIMM per channel (and the higher supported speed) while leaving room to grow.

The cheapest SK hynix module is the one that boots at full speed the first time. Start from the server's qualified part list, then compare prices.