Synology RAM upgrade not working

Synology not recognizing RAM. Same RAM others claim to be working.

Few potential things to try before sending your RAM back to the shop:
-Try RAM installed before DSM7 upgrade
-RAM not working because CMOS has an error from a previously tried the incompatible RAM (if trying few different brands)
-HDD cache has logged failed RAM. Replace with original RAM before trying a new brand
– run Synology ram check via Synology assistant
-disable virtual machine RAM before removing physical stick
-RAM is physically damaged (static shock etc)
-RAM comes from different factories and different firmware
-RAM somehow didn’t click in a slot
-dual single rank RAM even though it sounds exactly the same by model

– remove original RAM before upgrading

-leave it for 10 minutes for RAM test to complete


Synology Unofficial Memory On DSM 7.1 – DS920+, DS220+, DS720+, DS420+ And DS1520+ NAS –…

Memory I tested in this video (with amazon links):

ADATA Adata Premier 4GB AD4S2400J4G17-B –
TimeTec 8GB 76TT26NUS1R8-8G –
Sabrent Memory 8GB SB-DDR8 –
Crucial 16GB CT16G4SFD8266 –
TimeTec 16GB 76TT26NUS2R8-16G –
Sabrent 16GB SB-DDR16 –
Transcend TS1GSH64V6B 8GB –
Transcend 2GB TS256MSH64V4X –

Other Memory that has been tested and worked:

Kingston KVR26S19S6/4 4GB –
AM-D4NESO-2666-4G 4GB –
Crucial CT4G4SFS8266 4GB –
TimeTec 76TT26NUS1R8-4G 4GB –
Transcend M2666HSH-4G 4GB –
SK Hynix HMA851S6CJR6N 4GB –
Crucial CT8G4SFS8266 8GB –
ATech AT8G1D4S2666NA0N12V 8GB –
ADATA AD4S3200716G22 16GB –


Samsung D4NESO-2666-4GDDR4 CL19 2666MHz CL194GBDS920+DSM 7.1[LINK] 26th Apr
Kingston KSM26SED82666MT/s DDR4 ECC CL19 SODIMM 2Rx82666MT/s DDR4 ECC CL19 SODIMM 2Rx8DS923+DSM7[LINK] 19th Nov
DUOMEIQI 1x8G-12800SLPC3-12800 DDR3 1600Mhz 8GB4+8GBDS918+DSM 7.1-42661[LINK] 1st Jun
DUOMEIQI PC3-12800 DDR31600Mhz 8GB 2Rx8 1.35V CL118GBDS918+DSM 7.1-42661[LINK] 22nd Jul
Crucial CT2K32G4SFD82662666 MHz CL192x32GBDS1821+7.0.1-42218[LINK] 27th May


If you like this service, please consider supporting us.
We use affiliate links on the blog allowing NAScompares information and advice service to be free of charge to you. Anything you purchase on the day you click on our links will generate a small commission which is used to run the website. Here is a link for Amazon and B&H. You can also get me a ☕ Ko-fi or old school Paypal. Thanks! To find out more about how to support this advice service check HERE   If you need to fix or configure a NAS, check Fiver   Have you thought about helping others with your knowledge? Find Instructions Here  


Or support us by using our affiliate links on Amazon UK and Amazon US

locked content ko-fi subscribe

DISCUSS with others your opinion about this subject.
ASK questions to NAS community
SHARE more details what you have found on this subject
CONTRIBUTE with your own article or review. Click HERE
IMPROVE this niche ecosystem, let us know what to change/fix on this site
EARN KO-FI Share your knowledge with others and get paid for it! Click HERE


53 thoughts on “Synology RAM upgrade not working

  1. If you replace the memory with an unofficial stick, you apparently void your warranty. Does the NAS remember that it had unofficial memory in it, if you swapped back in the official stick while still in warranty?

  2. I was able to upgrade my DS923+ (DSM 7.1.1-42962 Update 4) with 32gb for $150 using A-Tech 32GB (2x16GB) RAM Replacement for Synology D4ECSO-2666-16G, D4ES01-16G | DDR4 2666MHz PC4-21300 ECC SODIMM

  3. My understanding of RAM use, is that when you upgrade, it is advisable to use equal sized modules in each slot. It is also important, when adding a different sized RAM module, to ensure that it’s specification match those of the module already installed. Have I misunderstood this?

  4. I had the Crucial CT8G4SFS8266 8GB installed on my DS720+ since June 2022 and working fine. But it stopped working 2 weeks ago (Jan 2023). My DS720+ would not startup and had the dreaded flashing blue power light. According to Synology support docs, I was afraid I had a bad MB or power supply, but removed the Crucial 8GB and it booted just fine. So, either my RAM went bad, or Synology changed something with their recent DSM update that disabled my RAM. Any one else experience this?

    1. Yes, this could be true that DSM updates disable some RAM modules. But sometimes you need to leave it for an hour to run its internal checks before it can boot. There is no lights blinking or other form of feedback when these background tests are runing.
      Also check this list

  5. I have DS1821+ with 10Gbs network card. Running 6x 12TB discs in RAID6. I edit videos and pictures on the NAS.
    I am running 2x 4GB of official Synology RAM. I am tempted to upgrade to 2x 16 GB of unofficial. I have two questions:
    1. Will my warranty be void when using unofficial RAM?
    2. Can anyone detail performance increase when going from 8 to 32 GB in my usage scenario?

  6. I ordered the Timetec 4GB module and installed and when I checked the total it was saying 20GB! I checked the package the module it came in and it said 4GB. Then after further examination, it showed that the sticker that said 4GB was on top of another sticker. I peeled it off and looked at it……I was sent a 16GB, not 4GB! So that worked out in my favor. Somehow it got mislabeled. I only paid for the 4GB. BTW: it works fine, no issues.

  7. 920+ DSM 7.1.1-42962 upd2: Crucial CT16G43FRA266 (16Gb) didn’t work, NAS couldn’t start. I downgraded system to 7.0.1.-42218 upd5 – Crucial module still didn’t work. So I changed Crucial module to Kingston KCP426SD8/16 (16Gb). Boot process successfully finished after 2-3 min, Kingston module works fine. Upgrade to 7.1.1-42962 upd2 also finished well.

  8. I installed the Timetec 16GB DDR4 2666MHz PC4-21300 Non-ECC Unbuffered 1.2V CL19 2Rx8 Dual Rank 260 Pin SODIMM memory in my DS220+ and it recognized it without any problem, the memory review took just over 7 hours and had no problems, my DSM version: 7.1-42661.
    Thank you very much @NASCompares for this analysis. Greetings from Mexico

  9. Bought the crucial 16GB Module, and inserted it into my brand new 920+. I couldn’t get it to boot up, removed it and all was well…. but a it miffed I couldn’t get the ram to work. I saw this video and thought it I may be able to get it to work, but no such luck. I just keep getting the flashing blue light. In this state, how do you get the NAS to close down other than doing what you were doing…. ie holding down the power button until it switches off.

  10. I have bought Crucial CT8G4SFRA266 8gb ram. (Single rank) It seems to not work on DS420+ with version: 7.1-42661 update 4 Or have I bought the wrong memory? i have this ram running around 1 hour nothing happens.

  11. I’ve just installed the same TimeTec 16GB RAM on my 920+ and it’s working just fine. First boot was quick (not much more than a minute for all solid green lights) and the RAM is showing in Info Centre.
    The standard 4GB at idle I’d often see the RAM use around 27% with the NAS just sitting there at idle with a few network devices attached. Now RAM use is 4% at idle so plenty of headroom. I’ll have to load it with some tasks to test it under load.
    This video gave me the confidence to do the upgrade.

  12. I installed a SAMSUNG M471A2K43CB1-CTD 16GB 2666V (made in China) into the DS220+, but it did not work. The NAS keeps flashing the blue lights for more than 20 mins. I guess not all the RAM are supported.

  13. Thank you for your great work!
    I installed a Kingston 8GB (KCP432SS8/8) into my 420+ and am pleased to report, that it is working.
    One curious observation is that the memory graph in the “Resource Monitor” is stuck at 5% utilisation while the “Memory Composition” bar more informatively shows the allocation of the 2+8GB RAM. When I copied a 20GB file from the 420+ to my laptop, the “Cached” segment went up to 8.9GB at one time. Hope that demonstrates the 420+ / Celeron could handle and make use of >8GB RAM.

  14. I upgraded my 1821+ to 7.1 today and it runs with no issues on “unofficial” 2x Crucial 32GB = 64GB ECC memory (so twice the max. oficially supported size of 2x16GB).

  15. I use Synology 4GB DDR4 ECC Unbuffered SO-DIMM
    in my 920+. It’s recommended for RS1221RP+, RS1221+, DS1821+, DS1621+.
    I know they recommend non-EEC in the 920 but seems to work ok. Anyone know if this is ok?

  16. Have you ever tested G.Skill SO-DIMMs? Especially on a DS418Play? I’m looking at a set F3-1866C11D-16GRSL which have CL11-11-11-32 1.35v specs and wondering if it will work. They appear to be dual rank chips

  17. I have the following all running 7.1 with 3rd party memory installed…rs3614xs+, rs2416+, rs18017xs+, ds2415+ and ds2419+. The ds2419+ is 1st gen and runs 32GB even though official support is 6GB – it does complain about non-Synology memory but is used 24/7 with virtual machines, camera feeds and TimeMachine without any issues. All have been upgraded from 6.x versions through to the latest 7.1 over time.

  18. I held off on updating my DS920+ due to previous video and just updated successfully after watching this video (Timetec 8G). Thanks for the follow up and all the great work you do!

  19. When I saw the title screen, I was momentarily confused because the most recent edition is only DSM 5. Then I realized what channel I was on and that this probably isn’t a video about the Diagnostic and Statistical Manual of Mental Disorders.

  20. So I bought yesterday a the Timetec 16GB Memory for my new DS720+, I have two iron wolf 8GB drives and try booting my NAS, without drive and its just stays there with the blue light blinking, left it for hours without any drive and it didnt boot. Then I have installed both drives and then installed the memory and still keep blinking for a while… how much should I wait?? Does will it actually work???

  21. Interesting! I have question about PS5 hdmi bandwidth which is 32gbps! Do you think Hardware wise Sony can uncapped the signal to 48gbps for 12bit 4.4.4? Since many people dont know to go with cheaper C1 G1 (40gbps hdmi) or C2 G2 which support 48gbps hmid bandwidth!

  22. Fantastic! Seeing this gave me the confidence to proceed with a DSM7.0.1 to DSM7.1 update on my DS920+ with 16GB Crucial memory upgrade (total 20GB).
    Success! Previous recognition was a good indicator of future recognition (within reasonable limits of probability). Ta!

  23. To be fair to you, who would think that an electronic device that operates at billions of operations per second would take 15 minutes to be configured. And there is the question of why you didn’t seem to ever run into this prior to DSM 7.1. Without testing with the exact same revision that was used before there is no way to know if they updated something to mitigate the issue.

  24. And this is exactly the reason why I pay close attention to Synology’s compatibility HDD/SSD lists. While everything seems to have work out fine here and the “right way” for RAM compatibility, the implications of it not having done so are very different to if that were the case for drives. For RAM you can put back the original memory and still operate, albeit in a limited capacity if you need the additional memory, especially if you’re well above the stated maximum. For drives though, the moment Synology decides that “oh we don’t do that no more” or “the compatibility list is clearly stated” can be massively problematic. One’s drives aren’t something that we can simply take out and put in something else.

    It’s all well and good that people on the internet saying things are fine but at the end of the day they’re not the ones covering your warranty nor fixing/dealing with your problem. Granted my perspective is probably skewed as I often deal with businesses. That said, I often find individuals are far more susceptible to incompatibility issues as their budgets are often more constrained.

    Memory is usually an easy fix, drives are usually not.

  25. Possible influence because of the DSM-Release-Version ?

    In Robbies first Video ( beginning of Mai 22 ) on unofficial Memory his Synology DS 920+ had DSM 7.1 – 42621 running and issues with the RAM.
    In the comments on this Youtube-Video Martin Kesselaar posted to have no issues running DSM 7.1 – 42550.

    In the second Youtube-Video ( just released ) Robbie installed and ran DSM 7.1 – 42661 and seemed to not have any issues ( on the same DS 920+ ); neither seem to have others running DSM 7.1 with the 42661-Release ?!?!?
    So seem to

    To the ones who know way better than me: Is it possible that there were changes on RAM-recognition between these Release-Versions ???

    Greetings from Germany to everybody ( …..and the seagulls )


  26. Thanks for this update, your last video had me worried about updating DSM. I have a DS220+ which I have just updated to DSM 7.1.42661 and my 4GB Crucial memory is working perfectly. Model number CT4G4SFS8266.C8FF

  27. Outstanding video mate. Very informative and one can imagine not the easiest to do. Not to criticize mind you, but it seems as if the RAM swaps were done with NAS power leads intact. It seemed to work fine if that is indeed the case but perhaps not something one would recommended to the unwashed masses,…

    Either way 2 thumbs up. Keep up the good work????????

  28. I was cautiously concerned when I updated my 920+ to 7.1 as the Timetec 8GB Memory had been working. Thankfully no issues, and I ran the Synology Memory Test to be sure it was not going to throw any flags. Thanks NASC for your past advice and continued support!