Well, i made some improvement, but i cannot find a stable 24/7 setup. I was able to test these rams on 4500MHz@C16-18-18-28 1T, tRFC 280, and very thigh subs, with 1.58V. It was without maxmem, so there was no tweaking. I was able to boot and do some benchmark too with CL15, but it appeared slower than CL16. That was the very edge of the stability of these moduls.
What is bad, i could not work out a stable 24/7 setup, even if i loaded them on XMP I or II.

I am still trying, with maximum 1.5V. I am sure, memories are fine, it will be an issue with the IMC. I played a lot with the SA and IO voltages, but no luck so far.
What is interesting, on my daily 4133@C16-16-16-30 1T, tRFC300 with 1.45V and same thigh subs, it is stable, and i can boot up with Maximus Tweak on Mode 2. With Mode 1, there is no post. On 4500MHz, it does not post with Mode 2, 55 post code is coming up every time, i have to use Mode 1.
Do not understand the nature of the memory OC with Coffee lake. Honestly, maybe this is the only issue.