Dual Channel - Different Ram Size?

[Ja55ie]

So I currently have 1 stick of 2133 SODIMM DDR4 ram running in my i3 7100u Intel NUC. 

I am currently running just the one stick. My question is what are the requirement of running ram in dual channel ? Can I add the same model - 4GB version of this ram and run it in dual channel? So it would be 12 GB total with one 8GB stick and one 4GB stick. Or do I have to use the exact same 8gb version (16GB total) I currently have in order to have the full benefit of dual channel? 

 

tl;dr: Can I use different ram sizes for dual channel ? 

P.S., sorry if this was already covered on this site - couldn't find a straightforward answer. 

[Skiiwee29]

you should be fine. Caveat: There is still a chance it wont work, but chances are it will work just fine. 

[NelizMastr]

In a 2 module configuration, I'm not sure whether you can mix different sizes without problems. I know that in configurations with 3 or 4 sticks, you can run dual channel in configs like this:

 

3 sticks:

 

4GB/4GB/8GB for 16GB dual channel in 3 slots 

 

4:

4GB/8GB/4GB/8GB for 24GB dual channel in 4 slots, 12GB per channel.

 

How flexible the controller is in your case is trial and error I'm afraid, or maybe someone else here has tried it.

[Ja55ie]

5 minutes ago, NelizMastr said:

In a 2 module configuration, I'm not sure whether you can mix different sizes without problems. I know that in configurations with 3 or 4 sticks, you can run dual channel in configs like this:

 

3 sticks:

 

4GB/4GB/8GB for 16GB dual channel in 3 slots 

 

4:

4GB/8GB/4GB/8GB for 24GB dual channel in 4 slots, 12GB per channel.

 

How flexible the controller is in your case is trial and error I'm afraid, or maybe someone else here has tried it.

I was afraid of you saying trail and error Haha. Thank you for the help! 

[Ja55ie]

9 minutes ago, legacy99 said:

you should be fine. Caveat: There is still a chance it wont work, but chances are it will work just fine. 

Thank you! Would you know how to tell if it would be working fine in dual channel? Would it say somewhere? 

[NelizMastr]

2 minutes ago, Ja55ie said:

Thank you! Would you know how to tell if it would be working fine in dual channel? Would it say somewhere? 

You can always double-check by running CPU-Z. The memory tab should say the amount of channels in use.

[Ja55ie]

12 minutes ago, NelizMastr said:

You can always double-check by running CPU-Z. The memory tab should say the amount of channels in use.

Thank you! 

[DocSwag]

If the mobo supports flex more it should run dual channel until you've used more than 8gb, at which point it will go to single channel.