[SOLVED] Best RAM configuration with 2x8GB & 1x16GB (Three cards)

Jan 25, 2019
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Hi.

I have a Ryzen 7 1700 (8 Core), with 2x8GB Hyper X Fury 2666.
I have just received another RAM chip, a 16GB HyperX Fury 2666.

I use this machine for 3D modeling and rendering.

What is the best configuration for my 3 x RAM chips on one ASUS PRIME X370-A Mobo with 4 slots (2 channels)
 
Solution
If you use more than 16GB of RAM, meaning you have checked a monitoring utility or resource monitor, and are running low on memory during operations, then you MIGHT benefit from installing the other stick, and you might not even lose the dual channel operation from the two sticks you already have installed so long as THEY are in the A2 and B2 slots. But you MIGHT lose their dual channel operation which would be a hit to the memory bandwidth if you do.

I'm not sure there are any Ryzen systems that support any kind of FLEX mode operation or not honestly. That would be where the two matching sticks, installed in one channel (A2, B2) DO work in dual channel while the oddball stick operates only in single channel.

Otherwise, if you are...
If you use more than 16GB of RAM, meaning you have checked a monitoring utility or resource monitor, and are running low on memory during operations, then you MIGHT benefit from installing the other stick, and you might not even lose the dual channel operation from the two sticks you already have installed so long as THEY are in the A2 and B2 slots. But you MIGHT lose their dual channel operation which would be a hit to the memory bandwidth if you do.

I'm not sure there are any Ryzen systems that support any kind of FLEX mode operation or not honestly. That would be where the two matching sticks, installed in one channel (A2, B2) DO work in dual channel while the oddball stick operates only in single channel.

Otherwise, if you are not running low currently on memory due to large project resource requirements of the programs you run, then you'd probably be better off just sticking to the 16GB dual channel configuration you already have. If you can find another matching stick for your 16GB stick and pair it with the one you have now, and repurpose the other two sticks elsewhere or sell them, that might work better for you. Or even add it TO those sticks, but I'll tell you that anytime you start adding oddball or mixed memory together you start increasing the probability that one or more of them is not going to want to "play nice" with the others.

*Resolving memory problems and setting up XMP/DOCP/AMP profiles

As is, you probably want the two existing sticks in the A2 and B2 slots and the other stick in either of the other two slots. Doesn't really matter which of the other slots that stick is installed in. If it interferes with your CPU cooler being in the slot closest to the CPU, use the other open slot.
 
Solution
Jan 25, 2019
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Thank you for the very informative answer!

I bought the new stick on a special, otherwise I might have waited and gotten 2x8. However I do require more RAM, I recently finished a project where My 16GB where used to the max on these large 3D files.

 
So, my advice would be to install them as I outlined. AMD does support FLEX mode where 8+8 should be running in FLEX mode and the remaining 16GB running in single channel, but I can't guarantee that any specific board supports it so you'll probably want to download CPU-Z and check the memory and SPD tabs to see what it's showing. On the SPD tab you'll need to select each specific DIMM slot from the drop down menu to see the report on that particular module.

In a case where you ARE running out of memory, it's probably better to have more memory than dual channel memory if you have to choose between the two, anyhow. If you could get another stick like that 16GB stick you have and just run those two together you'd be better off (IF they play nice together, since memory not purchased as a set always stands of chance of having incompatibilities, even with identical part numbers) anyhow as you'd have more memory plus dual channel, and may even be able to run all four sticks although I wouldn't bet the house on it with Ryzen, at least not at full advertised speed.