RAM pairs with different CAS latency mounted: F4-3200C16D-16GTZ & F4-3200C16D-16GTZB

[gkillz]

I far as I know I can use RAM with slightly different CAS latency. I mounted the G.Skill Trident Z F4-3200C16D-16GTZ (2x8) and planning to buy G.Skill Trident Z F4-3200C16D-16GTZB (2x8) which are slightly slower and mount them in the remaining two empty slots of my ASRock Z170 Extreme4 mobo.
These two RAM pairs are matching on size, speed, CL latency and obviously manufacturer/model.

The complete Tested Latency (from G.Skill) profile for this models is:
F4-3200C16D-16GTZ 16-16-16-36
F4-3200C16D-16GTZB 16-18-18-38

My UEFI is left to automatic settings, it will set the speed and timing for all the RAM at the pair with the slowest specs embedded in its SPD or the system is going to crash?
If the hardware retains its working stability, how much of a deterioration in performance I am exposing myself to?

Thanks in advance for any useful info!

[GSKILL TECH]

It is not recommended to use RAM with slightly different CAS latency. In some cases even the same exact model, latencies, and Voltages can not work well together so mixing different memory is not the ideal path.

A single 32GB+ kit is best to replace the existing memory kit.

If the system is stable, there should be no problem or deterioration. Question is if they can be stable at default, then if they can run a higher DRAM frequency at all.