What is the chance that the memory will start at adequate timings and voltage?

Question

RAM

CMR16GX4M2C3200C16 (2x8) and CMK16GX4M2A2666C16 (2x8) memory available. Both sets of dies are +\- of the same generation.

CMR16GX4M2C3200C16 from the factory has XMP: 1.35v 16-18-18-36 @3200

CMK16GX4M2A2666C16 from the factory has XMP: 1.2v 16-18-18-35 @2666

And the same SPD is sewn on both dies from the factory: 1.2V 15-15- 15-36 @2133

Tested from network CMK16GX4M2A2666C16 works stably at 1.2v 17-19-19-38 @3200

It seems like... 1.35v is considered a safe voltage for DDR4 memory.

Do you think this thing will fly in 4x8 1.35v 17-19-19-38 @3200 format?
Or is it better to find a middle ground ~ 4x8 1.3v 16-18-18-36 @3000 or something similar?
Task: maximum memory speed while maintaining 100% stability.

Mother ASUS PRIME Z390M-PLUS
@2666
@3200

Answer 1

none,
it all depends on the given instance,
i.e. if uncle Vasya works the same with overclocking, it’s not a fact that it will work for you

Answer 2

"Everything is stolen before us." - law of life.
Obvious fact - Faster memory costs more!
At the factory (naturally) ALL chips are checked and sorted.
Therefore, if they indicated some values, then 100% can be overclocked ONLY at the expense of stability.
Price is the best indicator of memory speed.
All discussions about overclocking are based on the romantic assumption that a powerful fan of fast hertz sitting at home knows exactly how to turn everything on correctly and deceive these stupid chip manufacturers.

Answer 3

At what frequency above the standard one all the dice will start, no one knows, this is a lottery, you can only put the dice and drive them in turn, determining their maximum, then run at some minimum operating frequency.
But there is a high probability that xmp will not start above.