I ended up getting the memory kit from framework to ensure compatibility in the early batches and I have 2x32GB and they are CL 46. I have ran into problems in the past with having to tight of timings with large capacity of ram and cpus memory controllers not being able to handle it. I am not really sure what the limits are for the 7840U because for a laptop I just want it to work and didn’t explore those things.

No it’s on my to-do list now but I would imagine having pre allocated the ram for the GPU would reduce memory management overhead.