Which RAM Fits Your Synology NAS? Model-by-Model Memory Guide

Short answer: every current Synology NAS uses DDR4 memory — there is no DDR5 anywhere in Synology's lineup — but the module type differs by model: non-ECC SODIMM, ECC SODIMM, ECC UDIMM or ECC RDIMM, with DDR3L in the 2017–2018 generation. Find your model below to see the Synology part number it takes, the maximum memory Synology specifies, and the matching NEMIX module.

How do I find which RAM my Synology NAS needs?

Check the model name on the front panel or in DSM under Control Panel → Info Center, then find it in the tables below. The model suffix matters: the RS2423RP+ and RS2423RP+II, for example, take different Synology modules, so each is listed separately. Maximum-memory figures come from Synology's own product specifications.

Which Synology models use non-ECC DDR4 SODIMM memory?

Synology's compact Plus models — DS224+, DS225+, DS425+, DS423+, DS220+, DS420+, DS720+, DS920+ and DS1520+ — have memory soldered to the board plus one open SODIMM slot. Synology caps most of them at 6GB (2GB onboard + one 4GB module); the DS920+ reaches 8GB (4GB onboard + 4GB), and the DS1520+ ships with 8GB (4GB onboard + a 4GB module). The RS820+ takes a single module up to 16GB. All use standard, non-ECC DDR4 SODIMMs.

Also covered: DS2419+, DS1819+, DS1618+ — see our D4NS2133-4G equivalent.

Which Synology models use DDR4 ECC SODIMM memory?

Most current DiskStation Plus and xs models use ECC SODIMMs, the small laptop-size module with error correction. The 2025 lineup (DS925+, DS725+, DS1525+, DS1825+, RS826+, RS1226+) uses Synology's D4ES03 modules; the 2022–2023 models (DS923+, DS723+, DS1522+, DS1823xs+, DS2422+, RS822+) use D4ES01/D4ES02; the 2021 models (DS1621+, DS1821+, DS1621xs+, RS1221+) use D4ES01-8G or D4ECSO-2666-16G. Two-slot models max out at 32GB (2×16GB).

Also covered: DS2419+, DS1819+, DS1618+, DVA3219 — see our D4ECSO-2666-16G equivalent.

Which Synology models use DDR4 ECC UDIMM memory?

Mid-range RackStations, the FS2500 and the dual-controller UC and SA units use full-size ECC unbuffered DIMMs (UDIMM). Two-slot rack units such as the RS2423+ and RS2825RP+ reach 32GB; four-slot xs models such as the RS3621xs+ and RS1619xs+ reach 64GB. On the UC3200, UC3400, SA3200D and SA3400D, memory is installed per controller; install the same memory in both controllers.

Also covered: RS2418+, RS2418RP+, RS2818RP+, RS3617xs+, RS3617RPxs, RS4017xs+ — see our D4EC-2666-16G equivalent; RS2418+, RS2418RP+, RS2818RP+ (non-ECC option) — see our D4NE-2666-4G equivalent.

Which Synology models use DDR4 ECC RDIMM memory?

Synology's high-end systems — FlashStation all-flash arrays, SA-series scale-out units, the HD6500, PAS7700, RS xs+ flagships and the ActiveProtect DP backup appliances — use registered ECC DIMMs (RDIMM). Capacity ranges from 64GB on the RS1626xs+ and DP5200 to 1TB (16×64GB) on the RS11626xs+, FS6420 and SA6400.

Also covered: FS3017, FS2017, RS18017xs+ — see our RAMRG2133DDR4-32G equivalent.

Which older Synology models use DDR3L memory?

Synology's 2017–2018 generation uses low-voltage DDR3L SODIMMs (1.35V). The DS918+, DS718+, DS218+, DS418play and DS620slim take DDR3L-1866; the DS1817+, DS1517+, RS1219+, RS818+ and RS818RP+ take DDR3L-1600. Match the speed to your model — Synology lists different modules for the two groups.

Synology memory part number cross-reference

Already know the Synology part number? Each Synology module below links to the NEMIX module matched to the same type, speed, voltage and rank.

Synology memory FAQ

How much RAM can a Synology DS923+ take?

The DS923+ has two DDR4 ECC SODIMM slots and ships with 4GB. Synology's maximum is 32GB (2×16GB). Compatible Synology modules are D4ES02-8G and D4ES01-16G.

What is the maximum memory for the DS224+, DS423+ and DS425+?

6GB. These models have 2GB soldered to the board and one SODIMM slot, and Synology specifies a single 4GB DDR4 non-ECC module (D4NS01-4G or D4NESO-2666-4G) for that slot.

What RAM does the Synology DS925+ use?

DDR4 ECC SODIMM — Synology's D4ES03-8G or D4ES03-16G — in two slots, up to 32GB (2×16GB).

Why does my Synology run DDR4-3200 memory at a lower speed?

The processor sets the memory speed. The AMD Ryzen V1500B and R1600 in models such as the DS925+, DS1825+ and DS725+ run memory at DDR4-2400, and the Intel Xeon D-1700 series in the RS1626xs+ and DP5200 runs it at DDR4-2933. A DDR4-3200 module runs at the platform's speed, which is normal and expected.

Can I use non-Synology memory in a Synology NAS?

Yes, the memory slots accept standard modules. Synology's compatibility list only covers Synology-branded modules, and Synology support may ask you to reinstall the original memory while troubleshooting, so keep the factory module. NEMIX modules are matched to the type, speed, voltage and rank of the Synology part they replace.

Should I use ECC or non-ECC memory in my Synology?

Use the type your model was designed for. Models built for ECC memory (all ECC SODIMM, UDIMM and RDIMM models above) should get ECC modules, and the compact Plus models with onboard memory use non-ECC SODIMMs. The tables above list the correct type for every model.

Buying for a fleet or a business?

Every module on this page is researched, matched, and compatibility-tested by NEMIX RAM, a US-based server memory specialist since 1993, and backed by a lifetime warranty. For multiple units, resellers or IT departments, request a volume quote — or browse all NAS memory upgrades.