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FREE 30-day refund/replacement
To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.
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Availability:
Only 1 left in stock, order soon!
Arrives
Thursday, Nov 5
Recently Viewed
At a glance
- Condition
- New
- Style
- 16GB
- Model
- D4ECSO-2666-16G
- Memory
- 16 GB
- Weight
- 1.12 oz
- RAM Memory Technology
- DDR4
- Memory Speed
- 2666 MT/s
- Warranty
- 5 Years
- Works with
- Synology devices
Features 2
- Synology RAM DDR4-2666 ECC SO-DIMM 16GB
- Compatibility - Applied Models: 21 series: RS1221RP+, RS1221+, DS1821+, DS1621xs+, DS1621+, DVA3221; 20 series: RS820RP+ (does not support the ECC feature, regardless of whether the expansion memory is ECC or non-ECC); 19 series: DS2419+, DS1819+; 18 series: DS3018xs, DS1618+; 17 series: DS3617xs
Description
Always select authentic Synology memory modules for optimum compatibility and reliability. Installation of non-Synology memory modules can lead to system instability or boot failures. Synology will not provide complete product warranty or technical support if non-Synology memory modules are used for memory expansion. For more information on memory upgrade limitations, visit Synology website.
Specs 23
| Brand | Synology |
|---|---|
| Computer Memory Size | 16 GB |
| RAM Memory Technology | DDR4 |
| Memory Speed | 2666 MT/s |
| Additional Features | Built and designed for maximum performance and reliability in Synology devices |
| Voltage | 1.2 volts |
| Form Factor | SO-DIMM |
| Data Transfer Rate | 12 Gbps |
| Number of Pins | 260 |
| Memory Form Factor | SODIMM |
| Memory Generation | DDR4 |
| RAM Size | 16 GB |
| Model Name | D4ECSO-2666-16G |
| UPC | 846504003679 |
| Number of Items | 1 |
| Manufacturer | Synology |
| Unit Count | 1 Count |
| Global Trade Identification Number | 79, 76 |
| Built-In Media | Synology 16GB DDR4 2666MHz ECC SO-DIMM Memory Module |
| Item Weight | 1.12 ounces |
| Item Type Name | RAM Module |
| Model Number | D4ECSO-2666-16G |
| Mfr Part Number | D4ECSO-2666-16G |
No specs match.
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Thursday, Nov 5
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
Synology RAM memory works!
Style: 16GB
Was using generic ram memory modules but always had problems. Now with the Synology ram memory modules the problems are no longer an issue. They were expensive but they work!
Reviewed in the United States on June 17, 2026 by M C
Real Synology RAM
Style: 16GB
People leave negative reviews on here due to the price tag. I get it. You CAN buy cheaper RAM. However, doing so voids your Synology Warranty. They don't hide that. If you don't like the price of their RAM, then either don't buy a Synology or go into that purchase knowing you plan to void the warranty. Don't come leave a negative review because you don't like the price. The product arrived exactly as advertised: Real, legitimate (see photo) Synology RAM. Maybe the other reviewer purchased from someone else, I'm really not sure. Installation is a breeze. I put this into my new DS 1621+ by moving the original 4G Stick to Bank B and installing the new 16G Stick into Bank A. Booted right up without any issues and a cool 20G of RAM in the system now.
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Reviewed in the United States on February 12, 2021 by Michael
Synology product
Style: 16GB
Everything was ok.
Reviewed in the United States on June 28, 2025 by Fernando Moreno Julio
Great but expensive
Style: 16GB
Worked as described but an expensive productive. Shipping was good and arrived on time and good shape.
Reviewed in the United States on July 19, 2024 by Johnny
Works great in Synology DS1821+
Style: 16GB
Purchased a pair of these to upgrade the RAM in a Synology DS1821+. These are working as advertised, and as they are on Synology's supported device list for the model I know they will not cause warranty issues should something happen later.
Reviewed in the United States on May 24, 2022 by DBJ
Arguably overpriced, works as expected
Style: 16GB
There is a huge debate with Synology requiring in-house products in order to maintain the warranty (probably illegal) or customer support (not very ethical). It is not unusual behavior. DELL, IBM, and HP require in-house components in their servers too. This extends to many other industries as well. As consumers, we either put up with it or vote with our wallets to push for change. I installed this in a 1621xs+ NAS. There is no sugarcoating that this model NAS is on the border of requiring either Enterprise grade Synology or Enterprise grade through other vendors for every component. Either way, you are paying a premium for any upgrades. The installation is simple. Power down the NAS. Unplug the power and Ethernet cables. Ground yourself. Remove the two screws on the bottom plate to expose the RAM. Remove the old DIMM. Install the new DIMM. Reverse the previous steps. The NAS fired back up, now showing 32 GB or RAM. Ho hiccups. The only potential issue is if you mix DIMMS. The 1621xs+ white sheet specifically states to either have one DIMM or matched DIMMS. Double check your specs if you plan on mixing DIMMS. Depending on your workloads, you will either see better performance including lower queues for the processor or less usage of the CPU since you don't have to cache as much. Either way, your NAS will perform better. Is it worth it? If your workloads are keeping your CPU above 25% usage at rest, you need more RAM. If you don't like waiting for I/O requests, this will help. If you are a light user, this isn't necessary. Now for the debate. If you install non Synology RAM, you will receive warnings about warranty and support. It is on you to determine if you wish to ignore the warnings. It is also on you to determine the risks of causing instabilities on a NAS due to non supported RAM or other components. There are documented cases that some RAM can cause the NAS to reboot which can cause data loss. Uncontrolled reboots with NVMe cache or an expansion unit almost guarantees RAID failure. I do not like rebuilding RAIDs. Depending on the size of the RAID, it takes days to weeks. Unless you have a recent backup, there is a chance of extensive data loss. For those reasons, I paid for Synology. If you still wish to save money, the DIMMS look like Samsung RAM to me. Make sure you get ECC DDR4-2666.
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Reviewed in the United States on February 7, 2023 by Amazon Customer
Works great, but overpriced. Required if you call support.
Style: 16GB
The only reason you'd ever pay this much $$$ for RAM is because Synology forces you to if you ever contact technical support and have issues. Why they can't test/validate other RAM which is 1/2 the cost is simple- they're just taking advantage of their customers. Only good thing is the AWS return policy so you can install the RAM, take a photo and show it to Synology support. Other RAM works just as well.
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Reviewed in the United States on April 25, 2023 by Aaron Turner
DO. NOT. BUY. Synology is a fraudulent company.
Style: 16GB
DO NOT BUY ANY SYNOLOGY PRODUCTS. I purchased a DiskStation 4 months ago. After a frustrating 5 hour process, I finally got it to be recognized on my network and function how it should. 3 months later, Synology changed their compatibility list and REMOVED MY DRIVES causing them to stop working entirely. I called their "customer support" and after 5 minutes of dealing with a robot I finally got someone on the phone. I described the issue and they put me on hold. 25 minutes later the hold music stopped and they hung up. 5 more calls before I finally got a different person to actually help create a ticket (only doable with customer support). 2 days later they finally responded to the ticket basically saying I have to buy their marked up drives if I want to continue using their product. This is unacceptable.
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Reviewed in the United States on February 20, 2026 by Amazon Customer