Config 3970x - RAM Kit (2x128GB) or (1x256GB)?

Hi everyone,

I’ve just subscribed to this forum after having seen during my long, long research on my config for my new workstation, the 2 excellent videos

  • OLOy: 128gb Threadripper 3960X 3970X Memory Tested


  • Checking Out GSkill’s NEW 256GB/3600Mhz Threadripper RAM

In fact, I am having a hard time to figure out if (2x128GB) kit (F4-3600C18Q2-128GTZN) from G.Skill would be as good as a single 256GB kit (F4-3600C18Q2-256GTZN).

“Hard time” because from the datasheet of the Threadripper 3970x, it is mentioned that this processor support only 4 channels memory, and I was wondering what could be the engineering magic trick from G.Skill to make the 256GB more efficient than 2x128…

My dilemma, is that I am building this config based on,

CPU - AMD TR 3970x
Mobo - Asus Zenith II Extreme Alpha

for CG/VFX purpose, which can require a large amount of RAM in liquid/fire simulation.

The 128GB kit could/should be perfectly fine, but if I needed to upgrade to 256GB in the futur, and had a bottle neck because I’ve choose the cheaper solution at first, this would have been a poor decision very unsatisfying.
Better invest in the 256GB kit right the way and secure many years of tranquility.

So if any of you could enlighten me on this matter, I would really appreciate your help.

Are you getting more than one? Not populating all your memory channels will be a big bottleneck


Agree with GigaBusterEXE here. If you’re looking for a total 256GB for the system in total, then at the very least you should get four 64GB sticks. This will give one stick per channel. Threadripper motherboards have eight slots though (two for each channel), and what Zen (the microprocessor architecture underlying Threadripper) likes the most is both slots per channel populated, so if it were me and I wanted 256GB RAM in total, I’d go for eight 32GB sticks.


Maybe I have not been clear enough.

The Asus Zenith II Extreme Alpha have a capacity of 256GB, with 8 slots (max 32GB of RAM per slot)
I am planning to use only 32GB of modules in any case (minimum 4x32GB), as this config have to be easily upgraded (64GB of RAM is out of question, as way to low for fluid simulations).

My question is really to know if there is a difference in performance between 2 kit of 128GB (4x32GB) (F4-3600C18Q2-128GTZN) from G.Skill, and the other Kit 256GB (8x32GB) (F4-3600C18Q2-256GTZN) which is advertised as optimized, as the processor manage only 4 channels.

Sorry my English is far from being the best, so my explanation could be not as accurate as I would like.

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Not sure what that means.

Get the 8x32GB no question IMHO.

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This is the problem… What does it really mean?

Just sent an email to the tech support, to find out what could be the difference.
I’ll update this post if I get an explanation from them.

In the mean time, if anyone have the answer, I am still looking for it.

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Okay, I see what you are saying now. (It is also my fault for not looking at the model numbers you listed in your first post.) So you’re comparing two kits of 4 x 32GB versus one kit of 8 x 32GB. Between those two there is no difference whatsoever; it’s the same RAM modules, it’s just how many you are getting.

The benefit to the single 8 x 32GB is that they will likely be engineered in the same run of modules and will be more “in sync” (the silicon used will “match” so to speak) with one another. The two 4 x 32GB kits, could be manufactured at separate times and not be as “in sync”. It’s not that two 4 x 32GB kits will be incompatible, it’s just they may not work together as effectively. We’re talking nanoseconds of variance between the two options though. They also test the modules and group them together accordingly to account for variances; so two separate kits wouldn’t have been tested together.

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I think @anon35662433 gave you your answer. I wouldn’t sweat it @Richard.CG - either option will be 100% fine. They may try matching the DIMMs but my guess it’s mostly just marketing.

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This is absolutely what I wanted to know, thanks a lot!

Do you think, that it could be a problem later, during the profile setup in the bios to get the “3600Mhz” if I use in the futur 2x 128GB vs the 256BG kit (as the official memory speed for 256GB is only 2667)?

More info in this video, if you need,

  • Checking Out GSkill’s NEW 256GB/3600Mhz Threadripper RAM

Which make me think, that I should go for the 256GB if I want to be sure to be able to get this speed…
Pretty sure, if I take 2 kit not manufactured at the same time, will bring instability.

Doubt it. You’ll be fine either way.


Actually both kits will have modules that are at a base speed of 2667. In either case you will have to enable DOCP in bios/uefi to get the 3600 that is advertised. You will get 3600 with either option, but initially (when you first start the system after the sticks are installed) you will be at 2667, in bios you will then enable DOCP which will automatically get you 3600, on either option. So ultimately, either way it will work the same.

Edit: I did a little digging and I’m now seeing were the “Official 2667 support” number is coming from, that’s from first Gen Threadripper, where it’s listed on the page of Threadripper 1950X. If you look at the 3970X product page the “Official support” is actually 3200. So 3600 shouldn’t really be an issue. The video you’re referencing is over a year old also, so memory manufacturers and board manufacturers have had plenty of time to stabilize things.

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Ok, great to know. I was thinking that the manufacturing process could really have an impact on it.

Then i will go for only 1 kit of 128GB first, and add another one if needed.

Thank you very much guy’s, really appreciate your help.

If you want ECC memory, I’m sold on Kingstons memory for my upcoming Threadripper. 3200 instead of 3600, but pricing is only slightly higher than non-ECC. Worth checking out.

Already bought the 128GB kit from G.Skill yesterday… But thanks for the info!

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