Is it neccessary to use quad channel ram kits in threadripper 2950x instead of 2 or 4 dual channel kits?

[tesseramous]

Backstory: I'm doing a build with a x399 Fatality professional gaming motherboard and a threadripper 2950x. For RAM I impulsively bought a sale promotion of a single dual channel kit of G.SKILL TridentZ RGB Series 32GB at 3200cl14. I was going to wait until later to get another 32GB (probably black friday) and then much later to upgrade to the full 128GB if I ever needed it. However, after reading more about how bad threadripper is with just two RAM sticks, I think I need to go ahead and get the other 32GB RAM now. I do not want to use any 8GB ram sticks, in case I want to upgrade to 128gb in the future. So I am trying to decide whether to:

A) Add an old 32GB kit of 2666cl15 ram from another machine until buy another RAM kit.
B) Order another identical dual channel kit of G.SKILL TridentZ RGB Series 32GB at 3200cl14.
C) Return the unopened dual channel kit I ordered and buy a quad channel kit.

 

Instinctively, adding 4 identical ram sticks should be able to run at quad channel. However, I have read information about how only actual quad channel memory kits are validated to have the sticks work together in quad channel and there might be errors with multiple dual channel kits, which is why quad channel kits are sold that way and more expensive than dual channel kits. Meanwhile, I've also seen information that it doesn't matter as much on threadripper because there are two different dies each accessing their own two channels, and on top of that Threadripper 2 has an enhanced memory controller.

 

So I have these questions:

 

1. If I install the old mismatched 2666cl15 memory kit, will it run in quad channel with all 4 sticks running at 2666cl15?

 

2. If I order another identical 3200cl14 kit, will it run at quad channel with no potential problems? Or do I need to return the kit I have and buy a quad channel kit?

 

3. What about when I want to use 128GB with all 8 DIMMs populated in the future? Will it run at quad channel with 4 different dual channel kits of the same RAM, or do I need two quad channel kits of 4 sticks, or I do need one quad channel kit of 8 sticks?

 

Thanks.
 

[Jurrunio]

The answer for the topic question is 'yes' so I recommend option B

 

1. It's supposed to, but god knows if the BIOS is smart enough to do that. You might need to tune it that way yourself.

 

2. Yes

 

3. It's fine with 4 dual channel kits, but not using the same dual channel kit can be a problem if the BIOS is stupid, you will need to tune the timings further yourself.

[tesseramous]

Thanks. So what is with all that information about multiple kits being unstable together because they weren't produced at the exact same time with the exact same machinery and tested in a lab to work together? Is that just for intel or older memory controllers?