I got the CMK16GX4M2B3000C15B (same in blue).
First of all, I have to say that these RAM sticks are very good for their price (I got them for €103).
They were paired with Ryzen 5 2600 + MSI B450 Tomahawk (they were on the compatibility list).
It should be noted that they are possibly overclocked by their manufacturer, as they have a base VRAM voltage of 1.36V instead of the default 1.2V that all RAM sticks have.
Initially, they were running at 2133 with timings 16-17-17-35.
The XMP2 profile was set to 2998, 15-17-17-35, but it was giving me 16-17-17-35. All my attempts to set the CL to 15 were unsuccessful, it kept giving me 16.
So, I started manual overclocking. They worked fine up to 3533MHz.
I tested them at 3400, 3200, and 3000MHz.
At 3400, any change in timings would cause a crash and prevent the system from booting. However, at 16-17-17-35, they were stable and performed well.
I didn't spend much time on 3200, but I easily achieved 14-15-15-30 at 3000MHz. Any attempt to lower the CL or tRCD, tRP would result in a crash. I didn't try lowering tRAS further.
After many benchmarks at 3400MHz (16-17-17-35) and 3000MHz (14-15-15-30), I decided to stick with 3000MHz as I had similar results.
Note: The DRAM voltage was always set to 1.36V in all the above settings.
Edit (2 years later): Eventually, the RAM sticks were not stable. Although they seemed fine at times, the PC would restart on its own or the screen would freeze (requiring a manual restart). The RAM sticks were the problem.
Now, I have them running at 2933 with timings 14-16-16-34.
I will deduct one star because the XMP2 should have worked with CL15, but in reality, it gives CL16. Nonetheless, they are good RAM sticks, but they are not worth it with newer generation processors and motherboards!
Edit #2 - 07/7/21
I had issues again, with the entire PC freezing. I tried everything.
I got frustrated and decided to enable XMP to be done with it, but funny things are happening. Now, the RAM sticks with XMP2 are running at CL15, but at 2133MHz instead of 2933MHz.
I will buy different RAM sticks, these ones have tired me out. I'm leaving two stars, and that's being generous.