RAM compatibility checker & memory finder
Search the OEM memory part number your server, workstation or laptop takes and see the modules whose manufacturer states compatibility with it — or filter live catalog memory by generation, capacity, form factor and ECC.
RAM compatibility checker
Two ways in — the part number your system takes, or the spec.
Results are catalog listings whose manufacturer states compatibility with the part number you entered — the compatibility claim belongs to the module maker (Axiom, AddOn, Kingston and others) and is printed in their own listing text. We match on what they publish; we do not certify the fit ourselves. Confirm it against your platform’s qualified-vendor list, or send us the system model with a quote and a rep will check it for you.
Showing 24 of 6,941 memory modules
- AddOnAddOn JEDEC Standard 8GB DDR4-2666MHz Unbuffered Single Rank x8 1.2V 288-pin CL17 UDIMM - For Computer - 8 GB (1 x 8GB) - DDR4-2666/PC4-21300 DDR4 SDRAM - 2666 MHz Single-rank Memory - CL17 - 1.20 V - Non-ECC - Unbuffered - 288-pin - DIMM - Lifetime WarrantyAA2666D4SR8N/8G
$192.00
$118.00
105 in stock - Axiom Memory SolutionsAxiom 16GB DDR4 SDRAM Memory Module - For Notebook - 16 GB - DDR4-2666/PC4-21300 DDR4 SDRAM - 2666 MHz - 260-pin - SODIMMAX42666S19B/16GK
$308.00
$233.58
51 in stock - AddOnAddOn IBM® 00D5011 Compatible Factory Original 4GB DDR3-1600MHz Registered ECC Single Rank x4 1.35V 240-pin CL11 Very Low Profile RDIMM - For Server - 4 GB (1 x 4GB) - DDR3-1600/PC3-12800 DDR3 SDRAM - 1600 MHz Single-rank Memory - CL11 - 1.35 V - ECC - Registered - 240-pin - RDIMM - Lifetime Warranty00D5011-AM
$54.50
$36.23
534 in stock - AddOnAddOn HP® 726724-B21 Compatible Factory Original 64GB DDR4-2133MHz Load-Reduced ECC Quad Rank x4 1.2V 288-pin CL15 LRDIMM - For Server - 64 GB (1 x 64GB) - DDR4-2133/PC4-17066 DDR4 SDRAM - 2133 MHz Quad-rank Memory - CL15 - 1.20 V - ECC - 288-pin - DIMM - Lifetime Warranty726724-B21-AM
$1,680.00
$1,032.50
3 in stock - AddOnAddOn Cisco® HX-ML-X64G4RS-H Compatible Factory Original 64GB DDR4-2666MHz Load-Reduced ECC Quad Rank x4 1.2V 288-pin LRDIMM - For Computer, Server - 64 GB (1 x 64GB) - DDR4-2666/PC4-21300 DDR4 SDRAM - 2666 MHz Quad-rank Memory - CL19 - 1.20 V - ECC - Unbuffered - 288-pin - LRDIMM - Lifetime WarrantyHX-ML-X64G4RS-H-AM
$1,552.00
$953.83
1 in stock - AddOnAddOn Dell® A9031094 Compatible Factory Original 128GB DDR4-2400MHz Load-Reduced ECC Octal Rank x4 1.2V 288-pin CL17 LRDIMM - 128 GB (1 x 128GB) - DDR4-2400/PC4-19200 DDR4 SDRAM - 2400 MHz Octal-rank Memory - CL17 - 1.20 V - ECC - 288-pin - LRDIMM - Lifetime WarrantyA9031094-AM
$2,805.00
$1,682.54
4 in stock
Specifications are read from the manufacturer product title as supplied to us; where a value is not stated it is left blank rather than estimated. Every line is screened for TAA country-of-origin and NDAA §889 status before checkout.
Form factors
RDIMM vs UDIMM vs LRDIMM
The difference is where the memory controller’s command and address signals go. On a UDIMM — an unbuffered DIMM — they travel straight from the controller to every DRAM chip on the module. That is the simplest, cheapest and lowest-latency arrangement, and it is what desktops, workstations and many entry-level servers use. The catch is electrical: every rank you add loads the same lines, so platforms cap unbuffered configurations at a small number of modules per channel.
An RDIMM — a registered DIMM — puts a register between the controller and the DRAM chips to buffer those command and address lines. That single buffer cuts the load enough for a server to populate more modules per channel and reach far higher total capacity, at a cost of roughly one clock cycle of additional latency. Nearly every rack server on the market requires registered memory, which is why RDIMM is the largest form factor in this catalog.
An LRDIMM — a load-reduced DIMM — goes one step further and buffers the data lines too, through a memory buffer on the module. The controller then sees one load per module regardless of how many ranks sit behind it, and that is what makes very high-capacity modules and fully populated channels possible at all. LRDIMMs cost more per gigabyte and add a little more latency than RDIMMs, so they earn their place in memory-bound workloads — large in-memory databases, dense virtualization, big analytics nodes — rather than in general-purpose servers.
None of the three are mixable. A board qualified for registered memory will not post with unbuffered modules, mixing RDIMM and LRDIMM in one system is unsupported, and SODIMM is a physically shorter module for laptops and small-form-factor machines rather than a variant you can fit to a full-size board. Read the platform’s memory-population rules first, then filter to that one form factor and stay in it.
| Type | What it buffers | Typical use | Trade-off |
|---|---|---|---|
| UDIMM | Nothing — direct to the DRAM chips | Desktops, workstations, entry servers | Lowest latency and cost; lowest capacity ceiling per channel |
| RDIMM | Command and address lines | Rack and tower servers | About one clock cycle of latency for many more modules per channel |
| LRDIMM | Command, address and data lines | High-capacity and memory-bound servers | Highest capacity per channel; highest cost per gigabyte |
| SODIMM | Either, in a smaller package | Laptops, mini-PCs, small-form-factor | Physically shorter module — a different slot entirely, not an option on a full-size board |
Error correction
ECC vs non-ECC RAM
ECC memory carries extra check bits alongside each block of data, giving the memory controller enough redundancy to spot a flipped bit and repair it before the CPU ever sees it. Non-ECC memory has no such margin: a bit that flips passes through silently, and the result is a wrong number, a crashed process or a corrupted file with nothing in the logs to explain it. In a laptop that risk is small enough to live with. In a server holding virtual machines, records or a long-running computation, it is the reason ECC exists.
Whether you need it is usually not a preference. Server platforms typically require ECC and refuse to boot without it, while most consumer desktops and laptops do not support it at all — the controller simply has nowhere to put the check bits. Workstations are the genuine middle ground, where the platform supports both and the call comes down to what a silent error would cost you.
One point of confusion worth clearing up: ECC and “registered” are different things. ECC describes error correction; registered describes the buffering above. Server modules are usually both — an ECC registered DIMM — but ECC unbuffered memory exists for workstations and entry servers, so filter for the two properties separately rather than assuming one implies the other.
Method
How to check memory compatibility
Start from the system, not the module
Get the exact model — server line and generation, workstation model, or laptop part number — and the memory part number its manufacturer lists against it. That OEM part number is the single most reliable input any memory compatibility tool can take.
Run the part number through the checker
Third-party module makers print the OEM part they replace in their own listing text, so searching that string returns the modules whose manufacturer states compatibility with it. Treat the result as their claim, verified against your platform's qualified-vendor list before you order.
Match the four hard constraints
If you have no part number, filter instead on the things a platform will not forgive: DDR generation, form factor, ECC and registered/unbuffered, and the capacity each slot accepts. Get those four right and the module physically fits and posts.
Then check speed and rank
A module rated faster than the platform supports clocks down; a mixed set runs at the slowest member. Rank matters too — dual- and quad-rank modules load a channel more heavily, and most boards publish a population table capping how many of each you can fit per channel.
Populate channels evenly
Memory bandwidth comes from filling channels, not slots. Buying matched modules in the count your platform's channel layout expects is usually worth more than a marginally faster part in an unbalanced configuration.
This tool reads its specifications from manufacturer listing text and never estimates a missing value — an unstated field is left blank, which drops that module out of that one filter rather than into a guessed bucket. Compatibility statements belong to the module manufacturer, not to Uniqcli.
FAQ
Common questions
- How do I check whether RAM is compatible with my system?
- Start from the system, not the module. Get the exact server, workstation or laptop model and the memory part number its manufacturer lists for it, then run that part number through the checker above — it returns catalog modules whose own manufacturer states compatibility with it. If you do not have a part number, match the four hard constraints instead: DDR generation, form factor, whether the platform requires ECC or registered memory, and the capacity each slot accepts.
- What is the difference between RDIMM and UDIMM?
- A UDIMM (unbuffered DIMM) wires the memory controller's command and address lines straight to the DRAM chips — simplest and lowest latency, which is why desktops, workstations and entry servers use it, but electrical load limits how many modules a channel can carry. An RDIMM (registered DIMM) puts a register in between to buffer those lines, costing roughly a clock cycle of latency and buying far higher total capacity per channel. They are not interchangeable: a board qualified for registered memory will not post with unbuffered modules, and vice versa.
- What is LRDIMM, and when do I need it?
- An LRDIMM (load-reduced DIMM) buffers the data lines as well as command and address, so the controller sees a single load per module no matter how many ranks it carries. That is what makes very high-capacity modules and fully populated channels possible. It costs more per gigabyte and adds a little latency, so it belongs in memory-bound work — large in-memory databases, dense virtualization — rather than general-purpose servers.
- Do I need ECC memory?
- Usually the platform decides for you rather than the workload. Most server boards require ECC and will not boot without it; most consumer desktops and laptops do not support it at all. Where you genuinely have the choice — many workstations — ECC is worth it for long-running work where a silently flipped bit would corrupt a result rather than crash visibly. Check the platform's memory specification before ordering either way.
- Can I mix RDIMM and UDIMM, or different speeds, in one system?
- Registered and unbuffered modules cannot be mixed, and mixing RDIMM with LRDIMM is not supported. Mixing speeds is allowed on most platforms but the whole set runs at the slowest module's rate, and a module faster than the platform supports simply clocks down to what the controller runs. Mixing capacities and ranks is where population rules bite hardest — check the board's memory-population table before combining anything.
- Is third-party memory as good as the OEM module?
- Third-party module makers such as Axiom, AddOn, Kingston and Dataram build to the JEDEC specification and publish compatibility against a named OEM part number, typically with a lifetime warranty. Some OEM systems log an informational message for memory that is not on their own qualified list, and OEM support may ask you to reproduce a hardware fault with OEM memory installed. If that matters to your support contract, tell us and we will quote the OEM part instead.
- How accurate are the specifications shown in this tool?
- Every specification here is read from the manufacturer's own product title as supplied to us — nothing is estimated. Where a listing does not state a value, we leave it blank rather than guess, which means a module with no stated ECC status simply sits out the ECC filter instead of being placed in the wrong bucket. Every line is screened for TAA country-of-origin and NDAA §889 status before checkout.
Need help sizing a memory upgrade?
Send the system model, the OEM part number or a bill of materials — we match the module, confirm stock and TAA country of origin, and return one priced quote. No payment up front.