Memory on OptiPlex 5040 SFF

Hello to anybody, I am new here and I hope somebody can help me, thanks. I have an OptiPlex 5040 SFF and I want to put more rams. Now I have 4 gb ram, model MT8KTF51264AZ-1G9P1, I dont know what frequency and it works only on 1 and 2 slots, when I try to put in 3 and 4 power led blinks several time in loop. I want to know how to unlock all 4 slots ram and if I can use dd3 ram with 1333 mhz, thank you very much and sorry for my english A great day to all  

Hi and welcome to the forum.  Your English is fine, but can you just confirm, how much RAM did your PC have before upgrading, and how many RAM modules were installed.  If I understand correctly, you are looking to add a single Micron 4 GB module to your system as an upgrade?  Is that correct?

There is normally no way to "unlock" additional RAM slots - they should just work.  However, sometimes some combinations of RAM sticks can cause instability, or cause the computer to fail to start.

Hello JonuK, thanks for fast reply. At the moment, I have 4 gb, model MT8KTF51264AZ-1G9P1, on 1 and 2 slots it work, but 3 and 4 not, power led blink, maybe I need to unlock of something? And I also have 2 gb ram 1333 mhz ddr3, that works in my old pc but in this one, I tried to put in all slots but same, power led blink Thanks you. 

I'm not aware of any procedure for "unlocking" the RAM slots - if anyone knows any specific issues with Dell products then perhaps they can comment, but I've never heard of such a thing.  It's possible they are dirty from dust, and blowing them out with canned air might help.  Does the 2 GB stick you have any labelling on it, and if so what does it say?  And this 2 GB RAM doesn't work, on it's own, in any slot?

Okay, well same slot 4 gb works, but 2 gb doesnt work, but 2 gb works in the other pc. I will tell you what is on 2 gb label: FLFE85F-C8KF9 CEES, thanks again.

According to the Dell Owner's Manual for your Optiplex 5040 SFF https://dl.dell.com/content/manual22275055-dell-optiplex-5040-small-form-factor-owner-s-manual.pdf?language=en-us on Page 58 you have Four DIMM slots in two banks of two - thisimpllies you need to populate them in matched pairs.

The spec also says you need DDR3L DIMMs rated at 1600MHz.

You have two MT8KTF51264AZ-1G9P1 4GB modules which are rated at 1866MHz which is often fine as higher speed rating usually works.

The Dell Compatability Matrix https://www.dell.com/support/kbdoc/en-uk/000132428/dell-optiplex-memory-compatibility-guide confirms that the memory MUST be DDR3L (not plain old DDR3).

The spec also states that you can fit a maximum of 16GB - so you can only add two more 4GB matched modules of a suitable type and speed rating - ideally the same spec as your original modules.

Edited by GeoffK, 27 October 2024 - 06:09 AM.

Hello GeoffK, there are 2 types of Optiplex, SFF and MT, MT has 16 and SFF 32 gb ram maxim. Motherboards are very similar. I am a bit confused. I didnt said I have 2 MTK, only one, one module 4 gb and other 2 gb FLFE85F-C8KF9 CEES. I want to know why doesnt work or if this pc can use 2 gb ram or only 4 gb/ 8 gb module.

Sorry - confused by your description of your memory working in slots 1 and 2.

If you're trying to upgrade from 4GB to 8GB total, then your best bet is to either get a matched spec 4GB module to your existing one, or replace it with a single 8GB DDR3L module.

Don't forget that an old 32-bit OS will only "see" about 3GB of memory.

Your FLFE85F-C8KF9 CEES are plain old DDR3 not DDR3L, and too slow, so WILL NOT work in your DELL OptiPlex 5040 SFF.

Dont need to sorry. I was mean that slots 1 and 2 works, but not 3 and 4 on motherboard, slots of ram I try to upgrade to 6, 4 gb + 2 gb, from above. My os has 64 bit. Do you know how to make slots 3 and 4 works?

They should "just work" - but you probably need compatible DIMMs in slots 1 and 2 first - so far you have only tested with ONE compatible DIMM.

So I cant use only one piece of ram to test all slots?

Because I test 1st, second and works with same plate of ram, but 3 and 4 doesnt work, power led blink only.

As I mentioned you could attempt to blow out the slots with canned air, this might work if they are very dusty, but it's curious that slots 3/4 don't work at all.  It certainly can happen if there's unseen damage to the motherboard, for example. 

I concur that the 2 GB DIMM you mention is coming up as a KingMax DDR3 DIMM (1.5v), and not a DDR3L (1.35v) one, which could be why it does not work.  Getting one the same as your existing memory would give the best chance of success.  Certainly you need DDR3L memory anyway.

Normally, yes, you can use one known working DIMM to test each RAM slot of your motherboard. 

Thank you very much. My motherboard is already clean. I have tried in sequel, first slot, work, second work, 3rd and 4 doesnt work, same ram, very strange, and power led blink.

Have you tried one stick in slot one and one in slot three.

Hello Phill, yes, doesnt work, I mean, tried with same stick all 4 slots, only 1 and 2 works.