Mismatched RAM advise

[ssjwizard]

So while I do know its always preferable to have matched kits I have a unique situation.
So I am decommissioning old systems from my studio, and have a couple of older dell mini pcs I no longer need or want, and do not boot.
So rather than wasting time or money I decided to tear them down to their usable components.

And I have now a few extra sticks of memory that are compatible with some systems I am keeping going.

I have 2 ZBook G3s with 16Gb RAM currently.

Anyway with the extra RAM it will be possible to further upgrade the systems but its going to be mismatched. Now I figure since I am using stock timings this should be ok.
Original ram is DDR4-2133 CL15 8GB Samsung sticks. What I puled are a couple of DDR4-2666 CL 16 Micron multiple size sticks, all sticks rated for 1.2V.

According to the documentation it should operate at the slower sticks speed which is what I want, and to that end I assume the 2666 should be able to handle the slightly tighter timings of the 2133 memory.

For one I am thinking about doing 16 + 2x 8GB for one unit configured with 8Gb sticks in slot 1 and 3 and the 16Gb stick in slot 2 this should even out the loading on the memory controller ish??

Then the other unit I think I will just drop my 2x 4Gb sticks in and upgrade that one to 24Gb total. These are all matched 2133 CL15s so I forse no issue putting 1/3 and 2/4 in an 8Gb + 4Gb configuration.

Thoughts advise?

 

[Zerileous]

My first thought is 16GB is adequate for the ZBooks. Have you monitored your memory usage and noted that you are using 16GB or had memory based slow-downs?

You can probably drop them in and the board will figure out how to run them, with it being a large OEM laptop, I'm doubting that you will be able to do much tweaking from the BIOS so you'd just have to take what you can get in that regard. I don't know if the 2x8GB on one channel and 1x16GB in the other will work, but you can always try it and use CPU-Z to determine if it works in dual channel like you want.

 

[Woomack]

Most laptop RAM have JEDEC specs so it should work regardless of used IC. Motherboards usually take 1st RAM stick timings and set the same for all banks. However it checks max frequency and adjusts to the slowest module or default IMC settings. If any RAM stick is not recognized by the motherboard, then switch them in slots. Recommended used to be smaller capacity in the first slot, but I guess that in modern computers it doesn't really matter.

All laptops in DDR4 generation suppose to support 16GB sticks, so at least 32GB total RAM. If in laptop's specs is otherwise then it doesn't mean it won't work. It probably wasn't tested for the initial specs and documents were not updated later. The same is for many desktop motherboards.

2 different capacity sticks should still run in dual channel mode, but depends on the chipset and IMC, it can be asymmetric mode. In short, it may perform the same as symmetric or slower, but still much faster than a single channel mode.

 

[ssjwizard]

My first thought is 16GB is adequate for the ZBooks. Have you monitored your memory usage and noted that you are using 16GB or had memory based slow-downs?

You can probably drop them in and the board will figure out how to run them, with it being a large OEM laptop, I'm doubting that you will be able to do much tweaking from the BIOS so you'd just have to take what you can get in that regard. I don't know if the 2x8GB on one channel and 1x16GB in the other will work, but you can always try it and use CPU-Z to determine if it works in dual channel like you want.

You are correct in that 16Gb is functionally adequate for what they are used for most of the time. I simply feel like the extra RAM sticks are probably not worth trying to sell, so may as well try to use it.

Most laptop RAM have JEDEC specs so it should work regardless of used IC. Motherboards usually take 1st RAM stick timings and set the same for all banks. However it checks max frequency and adjusts to the slowest module or default IMC settings. If any RAM stick is not recognized by the motherboard, then switch them in slots. Recommended used to be smaller capacity in the first slot, but I guess that in modern computers it doesn't really matter.

All laptops in DDR4 generation suppose to support 16GB sticks, so at least 32GB total RAM. If in laptop's specs is otherwise then it doesn't mean it won't work. It probably wasn't tested for the initial specs and documents were not updated later. The same is for many desktop motherboards.

2 different capacity sticks should still run in dual channel mode, but depends on the chipset and IMC, it can be asymmetric mode. In short, it may perform the same as symmetric or slower, but still much faster than a single channel mode.

Capacity should be no issue. The spec on these computers is 4x16Gb DDR4-2133. And yes the 8Gb sticks are the slower ones also so I figured putting them in channel one, and the single 16Gb 2666 stick in channel 2 would give the most consistent results.

 

[WhitehawkEQ]

I would advise against it, but I can't stop you. From what I know from the MB manuals and my IT training, you don't mix ram speed, size and # of sides the ram has. It may work or you get the illusion it's working or not work at all.
Best of luck

 

[ssjwizard]

Well all went as expected and both systems completed a full system test after installing.




Seems to have worked out for a free all be it unnecessary upgrade