What setting for high capacity DIMMs?

[memphist0]

I am trying to combine a 64GB kit (2x32) and a 32GB kit (2x16) on a Ryzen 3900x and X470 motherboard. I can get either kit to run independently or both kits if I drop frequency down to 2400MHz. I know I had read before there were specific timing to increase to allow 4 higher capacity sticks to work at higher frequencies.

Anybody have some suggestions? I do know it is not the 4 primary timings, it is something in the sub timings.

Thanks

 

[EarthDog]

Never heard of that magic fix... but memory isn't my thing. You do NEED all of this RAM, right?
What motherboard, exactly? Are you on the latest bios.
Ram sticks. Exactly?

With that capacity, you're going to need to play with the SOC voltage too and raise it up for the IMC.

 

[Woomack]

I would check if the motherboard reacts better with 2x16GB or 2x32GB in the first slots. Usually, the motherboard takes timings from the first memory module and for sure secondary timings set by the motherboard will be tighter on 2x16GB than on 2x32GB. If it can't boot then it means that the motherboard is trying to set too low timings for 32GB modules. Putting 32GB in the 1st slot and setting manually higher clock like 3200 and something like CL18-20-20 1.40V should be enough (at least for start to check if it boots).
There can be also a problem that the motherboard can't handle all this RAM at a higher clock but it's hard to tell "remotely".

 

[memphist0]

Thanks for the ideas

Latest BIOS
The motherboard supposedly supports up to 128GB

I will try switching the slots the memory is in to see if that helps.

Right now all the timings are on Auto
But I grabbed DRAM Calculator to get the timings and subtimings the 2x32GB kit is using
I am thinking I set those manually and then install the 2x16

I figure it is worth a try

And to whether I need that much. I can get by with 64GB but the extra 32GB would be nice.

For work I run VMs that require between 16GB and 32GB and of course I need to leave some left over for the OS. The more VMs I can run simultaneously the faster I can get work done. We have a vSphere server at work but through VPN it is a nightmare.