Synology NAS Memory by OEM Part Number

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NEMIX RAM SYNOLOGY COMPATIBLE MEMORY UPGRADES

Synology Memory by Factory OEM Part Number

Synology sells memory under its own part numbers, and their pricing is famously not gentle. If you already know your Synology part number, find its equivalent here — same spec, lifetime warranty.

How to read a Synology part number

D  4      ES    01     -8G
│  │      │     │       │
│  │      │     │       └─ capacity (or speed, on older parts)
│  │      │     └───────── revision
│  │      └─────────────── memory type
│  └────────────────────── generation: 4 = DDR4
└───────────────────────── Synology DIMM

Code	Type	Parts here
`ER` / `RD`	ECC Registered — RDIMM	D4ER01-16G · -32G · -64G · D4RD-2666-16G · -32G
`EU` / `EC`	ECC Unbuffered — UDIMM	D4EU01-8G · -16G · D4EC-2666-8G · -16G · D4EC-2400-16G
`ES` / `ECSO`	ECC SODIMM	D4ES01-8G · -16G · D4ES02-8G · D4ES03-8G · -16G · D4ECSO-2666-16G
`NE` / `NESO` / `NS`	Non-ECC UDIMM / SODIMM	D4NE-2666-4G · D4NESO-2666-4G · D4NS2133-4G

Which memory your Synology takes

Synology uses four memory types across its lineup, and the part-number code tells you which one your unit needs. The form factor and ECC status are not interchangeable: a 260-pin SODIMM will not fit a 288-pin slot, and a unit designed for ECC will not treat a non-ECC module as equivalent.

Synology family	Memory type	Synology parts	Typical models
Plus-series desktop (current)	DDR4 ECC SODIMM, 260-pin	D4ES01, D4ES02, D4ES03	DS923+, DS1522+, DS723+, RS822+
Plus-series desktop (2020–2021)	DDR4 ECC SODIMM, 260-pin	D4ECSO-2666	DS1621+, DS1821+, DS2422+
Value Plus desktop	DDR4 non-ECC SODIMM, 260-pin	D4NESO-2666, D4NS2133	DS920+, DS720+, DS420+, DS918+, DS718+
xs / xs+ tower and mid-range RackStation	DDR4 ECC UDIMM, 288-pin	D4EC-2666, D4EC-2400, D4EU01	DS1618+, DS1819+, DS2419+, xs+ towers
High-end RackStation, SA and FS series	DDR4 ECC RDIMM, 288-pin	D4RD-2666, D4ER01	RS4021xs+, SA3400, FS3400 class

Model lists are representative, not exhaustive. The part number printed on your existing module, or listed on your model's specification page, is the authority. Match that and you have the right memory.

How to find your part number

Three ways, fastest first:

In DSM: Control Panel → Info Center → General shows installed memory. Storage Manager and the System Health widget also report total capacity.
On the module: pull the existing stick; the Synology label carries the D4-series part number.
On Synology's site: open your model's product page → Specifications → Memory. It lists the pre-installed module, the maximum, and the part number for expansion.

Then use the Shop by System Model filter on the left or search this collection by the part number.

What "same spec" means

A NEMIX RAM equivalent matches the Synology part on every attribute the NAS memory controller checks, not just capacity:

Generation and speed — DDR4-2666 (PC4-21300) or DDR4-2133 (PC4-17000), as the part specifies. Faster modules are not a bonus; the controller runs at its rated speed.
ECC status — ECC on ECC parts, non-ECC on non-ECC parts. ECC catches and corrects single-bit memory errors before they reach the file system, which is why Synology specifies it on units meant to run 24/7 with Btrfs checksumming.
Form factor and pin count — 260-pin SODIMM or 288-pin UDIMM/RDIMM.
Rank and voltage — the density organization (1Rx8, 2Rx8) and 1.2V operation the platform expects, so the module is recognized at full capacity.

Every module in this collection is matched to the Synology part it replaces. Researched, matched, and compatibility-tested by NEMIX RAM, a US-based server memory specialist since 1993, and backed by a lifetime warranty.

Capacity, kits, and the published maximum

Synology publishes a supported maximum for each model. Stay within it: a module above the ceiling may not be recognized. Two-slot units run best with a matched pair of identical modules, which is why the DS923+ and DS1522+ class ships here as both single sticks and 2-stick kits. If you are adding to a factory-installed module, match its capacity and part number rather than mixing sizes. Not sure what your fleet needs? Contact our sales team. We can quote any configuration, including volume and reseller pricing.

The DSM memory notice, explained

DSM may display a notification stating that a non-Synology memory module is installed. This is an informational label Synology applies to any third-party memory, not an error, and it does not restrict the unit's operation. The NAS boots, recognizes the full capacity, and runs normally. Synology's policy is to limit its own support to Synology-branded memory; NEMIX RAM stands behind these modules with a lifetime replacement warranty and free US-based technical support, so if anything is ever wrong with the module, we handle it.

Why NEMIX RAM

NEMIX RAM has been building and testing memory for servers, workstations, and storage systems since 1993, from the United States. Every module in this collection carries a lifetime replacement warranty. Because we match to the Synology part number rather than selling a generic module, you get the same specification the NAS was designed around, at a price that reflects the memory rather than the badge. Volume, reseller, and B2B pricing is available on request.

Frequently asked

Can I use non-ECC memory in an ECC unit to save money? Don't. Synology specifies ECC on those models for data-integrity reasons, and mixing ECC and non-ECC modules is not supported.

Can I use faster memory than the part specifies? The controller will run it at its rated speed at best; at worst it will not post. Match the speed on the part number.

Do I need to install matched pairs? On two-slot units, yes, for best results. Match capacity, part number, and rank.

Will upgrading void my Synology warranty? Installing memory is a user-serviceable operation on these models. Synology's hardware warranty on the NAS itself is not voided by adding memory, but Synology may decline to troubleshoot issues it attributes to third-party modules. That is what our warranty and support are for.

What does more memory actually do on a NAS? Larger read cache for frequently accessed files, headroom for Docker containers and virtual machines, smoother Synology Photos indexing and Plex transcoding, and fewer stalls with many concurrent users. On Btrfs volumes, more memory means more metadata stays resident.

Questions? We have Answers!