How to Install DDR4 ECC SODIMM Memory in a Synology NAS

A Synology NAS that takes DDR4 ECC SODIMM has one or two small memory slots and uses error-correcting laptop-size modules. Adding or replacing them takes about ten minutes and a screwdriver on some models, and no tools on others. This guide lists every Synology model in our catalog that uses DDR4 ECC SODIMM, then walks through the install: shut down, open the unit, seat the modules, and confirm the new total in DSM.

Which Synology NAS use DDR4 ECC SODIMM?

Most current Synology Plus and xs-series DiskStations, several RackStations and the FlashStation FS1018 use DDR4 ECC SODIMM. The tables below match each model to the module speed, the largest memory Synology specifies, and the Synology part numbers for that model. Every model links to its NEMIX listing, which offers the matching 8GB and 16GB modules and two-module kits. Capacities differ slightly by listing.

DiskStation (DS)

The neo+ models ship with one 4GB non-ECC SODIMM. They also accept Synology's ECC modules, but modules in a multi-module setup must be identical and ECC and non-ECC modules cannot be mixed, so replace the factory module when fitting NEMIX ECC modules. Listings: DS725neo+, DS925neo+, DS1525neo+, DS1825neo+.

RackStation (RS)

FlashStation (FS)

Your model is not here? Synology uses other memory in other models: non-ECC SODIMM in the DS224+, DS225+, DS423+, DS425+ and similar compact units, ECC UDIMM in mid-range rackmounts, and ECC RDIMM in the largest systems. The Synology NAS memory guide covers every type by model, and the Synology part number cross-reference lets you search by the Synology part number printed on a module.

Before you start

• Confirm your model and what is installed. In DSM, open Control Panel, then Info Center, and read the model name and the Total Physical Memory. Write both down.
• Match the module to the model. Use DDR4 ECC SODIMM only. It is the same physical size as DDR4 non-ECC SODIMM but is not interchangeable with it, and DDR4 and DDR5 SODIMM do not fit each other's slots. Do not mix ECC and non-ECC modules.
• Use matched modules. On two-slot models, fill both slots with modules of the same capacity. A two-module kit arrives matched, so it is the simplest route when you are replacing everything.
• Gather what you need. A small Phillips screwdriver for models with a cover, a clear table, and a way to ground yourself, such as touching bare metal on the unit before you handle a module.
• Back up first, and keep the original module. Make sure your data is backed up before you open any NAS. Keep the factory module in an anti-static bag. Synology's compatibility list covers Synology-branded modules, and Synology support may ask you to reinstall the original memory while troubleshooting.

About warranty. Synology states that it does not provide full product warranty or technical support when non-Synology memory is installed, and recommends its own modules. NEMIX RAM modules are researched, matched, and compatibility-tested by NEMIX RAM and are backed by a NEMIX lifetime warranty. Decide which support route suits your situation before you order, particularly for a NAS still under Synology warranty.

How to install DDR4 ECC SODIMM in a Synology NAS

Step 1: Check the memory you have now

Sign in to DSM as an administrator and open Control Panel, then Info Center. Note the Total Physical Memory. After the upgrade you will check the same screen. Note which slots are filled if you can see them later, because most models ship with one module installed and one slot free.

Step 2: Shut down and disconnect

Shut the NAS down from DSM using the power option under your account menu, and wait until the unit is fully off. Then unplug the power cord and every network, USB and expansion cable. Do not add or remove memory with the power on.

Step 3: Get to the memory slot

How you reach the slot depends on the model. Synology uses three layouts across the models above, and your model's Hardware Installation Guide on the Synology Knowledge Center shows which one you have.

• Behind the drive bays. On models such as the DS925+ and DS1522+, the memory slots are on the inner right side of the unit. Pull out all the drive trays to expose them. You do not need to remove the drives from the trays, but note which tray went in which bay.
• Under a bottom cover. On models such as the 6-bay DS1621+ and DS1621xs+, the slots are on the underside. Remove the two screws that hold the memory cover and lift it off. The drive trays can stay in place.
• Under the top cover. On rackmounts such as the RS822+, remove the screws on the top, slide the cover toward the front and lift it off.

Once the unit is open, touch only the memory assembly. Other internal parts are sensitive to static and to handling.

Step 4: Remove the old module if you are replacing it

If you are replacing a module rather than filling an empty slot, push the levers on both sides of the module outward. The module pops up at an angle. Lift it out by its edges. Hold every module by the edges and keep your fingers off the gold contacts.

Step 5: Seat the new module

Line up the small gap in the module's gold connector with the notch in the slot. Insert the module at an angle, then press it down firmly until the levers click. The module should sit flat and firmly in the slot. If you are installing two modules, fill slot 1 first and use two modules of the same capacity.

Step 6: Close up and power on

Put the cover back and tighten its screws, or slide the drive trays back into their original bays. Reconnect the power and network cables and press the power button.

Step 7: Confirm the new total in DSM

Sign in again, open Control Panel, then Info Center, and check Total Physical Memory. You can also watch Resource Monitor, then Memory. For a 2 x 16GB upgrade, expect 32GB. Run the NAS for a while under your normal load and check that it stays stable before you consider the job done.

If the NAS does not start or shows less memory

1. Shut down, unplug the power cord and open the unit again.
2. Reseat each module. Push it down until the levers click.
3. Check that the new modules are DDR4 ECC SODIMM and that you have not mixed ECC with non-ECC.
4. Test one module at a time in slot 1. If a single module works and the pair does not, the pair may not be matched.
5. Put the original module back to confirm the NAS itself is healthy, then send us your model and the part number on the module and we will help.

How much memory should you install?

Synology specifies the largest memory for each model, which is 32GB on most models in the table and 48GB on the DS3617xs, DS3617xsII and DS3622xs+. Pick the size for what the NAS runs. File sharing and backup use little. Containers, virtual machines, Surveillance Station, Plex and other media apps, and SSD caching all use more. A pair of 8GB modules gives 16GB, and a pair of 16GB modules reaches the 32GB maximum on two-slot models. Synology publishes its own recommended pairs for each model, and we list kits that match them.

Find your memory

• DDR4 ECC SODIMM, every ECC SODIMM listing we carry.
• Synology DiskStation memory, RackStation memory and FlashStation memory.
• The Synology memory hub page and the general NAS memory guide.
• Other brands: NAS memory by brand.

Buying for several NAS

NEMIX RAM is a US-based memory specialist, in business since 1993. Every module is researched, matched, and compatibility-tested by NEMIX RAM, is JEDEC-compliant, and is backed by a lifetime warranty. Offices with a NAS at each branch, schools and integrators can standardize on one kit per model and keep spares on the shelf. Purchase orders, net terms and volume pricing are available. Request a quote with your NAS models and quantities, or contact our sales team and we will confirm the right module before you order.

NEMIX RAM is an independent memory supplier and is not affiliated with Synology. Synology, DiskStation, RackStation, FlashStation and DSM are trademarks of Synology Inc., used only to identify compatible systems. Installation steps are summarized from Synology's published hardware installation guides; always follow the guide for your exact model.