Memory is the one NAS upgrade most owners can do themselves, and the one most often bought wrong. The reasons are always the same: the wrong generation, the wrong module type, ECC where it is not supported, or a capacity past the maximum. This guide is a seven-step sequence that removes the guesswork, followed by notes on each brand's naming and the shortcuts that work.
The short answer
Find the exact model name, check the maker's memory specification for generation, type, ECC and maximum, then buy the listing built for that model. Every NEMIX NAS listing is matched to one model, so the model name is the whole search.
Step by step
- Find the exact model name. It is on the label under or behind the unit and on the system information page of the web interface. Model names differ by one character between generations, so copy it exactly, including the plus sign or suffix.
- Check whether the memory can be changed at all. Some compact and entry NAS have memory soldered to the board and no slot. The maker's specification page says so, often as 'memory not expandable'. If there is no slot, stop here.
- Read the memory specification. From the maker's page or the NEMIX listing, note four things: generation (DDR3L, DDR4 or DDR5), module type (SODIMM, UDIMM or RDIMM), ECC or non-ECC, and the published maximum.
- Count the slots and what is in them. A two-slot model with one module installed can take a second matching module or a matched pair. A single-slot model with soldered base memory takes one larger module. The system information page shows what is installed.
- Decide on capacity. Pick the amount for the workload, within the maximum. Match modules when both slots are used.
- Match the module. Find the model's listing in the NEMIX NAS collection, or search by the maker's part number. The listing names the module type, the speed and the capacities built to that model's maximum.
- Install and verify. Follow the install guide for the brand, then confirm the full capacity on the system information page.
The four things that have to match
| Attribute | What it means | What goes wrong |
|---|---|---|
| Generation | DDR3L, DDR4 or DDR5 | A DDR5 module will not fit a DDR4 slot; the notch is in a different place |
| Module type | SODIMM (small), UDIMM (full size desktop), RDIMM (registered, servers) | Wrong type will not fit or will not boot |
| ECC | ECC or non-ECC | ECC in a non-ECC NAS runs as plain memory or fails to boot; non-ECC in an ECC-required NAS fails to boot |
| Capacity and maximum | Per module and total | Past the maximum, the NAS may ignore the extra or refuse to start |
Speed is the fifth attribute, and the forgiving one: a module of the right type at the maker's listed speed is correct, and a faster one usually runs at the listed speed. The memory types guide shows the physical differences, and ECC vs non-ECC for a NAS covers the ECC decision by platform.
By brand
Synology
Synology names its modules by code: D4ES01-8G is DDR4 ECC SODIMM 8GB, D4NESO-2666-4G is DDR4 non-ECC SODIMM 4GB, D4RD-2666-16G is DDR4 RDIMM 16GB. Ryzen-based plus and xs models take ECC SODIMM; Celeron and Atom models take non-ECC SODIMM; FS, SA, HD and the large xs rackmounts take RDIMM. Search the part number in the memory by Synology part number collection, or start from the Synology memory guide and the Synology hub. The neo models are covered in the DiskStation neo+ guide.
QNAP
QNAP part numbers read RAM-8GDR4ECT0-SO-2666 or similar: capacity, generation, ECC flag (EC), form factor (SO for SODIMM, UD for UDIMM, RD for RDIMM) and speed. The TS-x64 and TS-x53 desktops take non-ECC SODIMM or UDIMM; TS-h and TVS-h models take ECC UDIMM or ECC SODIMM by model; rack and enterprise units take RDIMM. The QNAP memory guide lists all 128 models with slots and maximums, and the QNAP collection has a listing per model.
ASUSTOR
ASUSTOR units take non-ECC SODIMM, DDR4 on older Lockerstor and Nimbustor models and DDR5 on the newer Lockerstor Gen3 and Flashstor Gen2. Several models have one slot beside soldered memory. The ASUSTOR memory guide and ASUSTOR collection cover every model.
TerraMaster
TerraMaster F, T and U series take non-ECC SODIMM, DDR4 on most and DDR5 on the 2024 and later models. See the TerraMaster memory guide and TerraMaster collection.
UGREEN
NASync DXP models take DDR5 non-ECC SODIMM, with 8GB fitted and two slots on most models; the iDX line has soldered memory. See the UGREEN memory guide and UGREEN collection.
TrueNAS and DIY
There is no NAS model, only a board. Use how to find compatible RAM for your motherboard and the board maker's qualified list.
Shortcuts that work
- Search the model name on nemixram.com. Listings are titled with the model, so the right one is the first result.
- Search the maker's part number from the spec page or from the label on the installed module. Synology and QNAP numbers are both indexed.
- Read the installed module's label if you have the unit open. The label gives generation, capacity, speed and ECC, and it is what to match.
- Ask. Send us the model name and we will confirm the module before you order.
Install guides
Synology ECC SODIMM, Synology RDIMM, QNAP, ASUSTOR, TerraMaster and UGREEN NASync. For the general sizing question, see how much RAM a NAS needs.
Frequently asked questions
Can I use laptop RAM in my NAS?
If the NAS takes non-ECC SODIMM of the same generation, a laptop module of the right speed usually works. Models that require ECC SODIMM or UDIMM need those types. Match the listing for the model and you avoid the guess.
Do I have to use the maker's branded memory?
No. The NAS takes standard JEDEC modules of the type it specifies. Makers sell their own branded modules and may limit support when other memory is installed; NEMIX modules are matched to each model and carry a lifetime warranty.
What is a Synology part number like D4ES01-8G?
It identifies a Synology memory module: D4 for DDR4, ES for ECC SODIMM, 8G for 8GB. NEMIX lists equivalents by those part numbers, so searching the number finds the matching module.
Can I install a faster module than the NAS specifies?
A faster module of the right type usually runs at the NAS's supported speed. It gains nothing. Buy the speed the model lists.
Buying NAS memory for one unit or a fleet
If the model is on the label, the module is in the catalog. Request a quote with your models and quantities, or contact our sales team. Related: NAS memory hub, business fleet memory and education and government.