I don't mean to be captain obvious, or to sound harsh, but what do you expect? Flawless operation?
There is a level of matching that is sometimes so specific that you need an exact same brand, same exact model, and same exact memory speed, same exact timings basically for everything to operate properly.
I bought 2 sticks of Fury HyperX, I thought they were all the same, but I was wrong, 2 sticks were 1866 mhz, one was 1600, and last one was 1333 mhz.
I had them all running in my system for about 3 years, until stutters got so ridiculous I sold my CPU, GPU, tried different motherboard, and it was all the ram issue.
Now my sticks are ruined, I literally will get random stutters even running two 1866 stock, and stock timings.
Unmatching your ram, and especially overclocking will potentially ruin your DRAM, and it doesn't matter how powerful or overclockable your ram was.
Match rams always, no different brands either, or you are bound for technical bs that will come with it.
Some people don't get the issue, but others do.
Worst part it will creep up, and then you have trash memory.
I have 4 sticks that still work, but 1 doesn't allocate memory in memtest86, just keeps cycling, but PC works on it just fine. The other stick takes 2 runs to allocate the ram in memtest86, other sticks are potentially at fault too.
So literally I have no DDR3 because of my "unmatching" 4 sticks of ram in my old system, and I will not sell it because I know it might cause identical issue for people.
And...that's just the tip of the iceberg, what about restarts, game crashes I had for years, and it was not CPU, it was not GPU, it was all ram.
Life teaches lessons, and now I rather follow electrical/schematic protocol, rather than wing it and hope for the best.
Assess the risks and make a decision.
If you overclock your ram, know that you are potentially trashing it, just know it. Don't be mad at manufacturers, because you are the one overclocking it.
I ruined 4 sticks. Ruined my gaming experience for years, because I never figured out my stutter issues, until I put the stick into another older x58 system in triple channel, and should I dare say "it trippled RAM issues"
Artifacts in all kinds of new ways I never saw.
Don't play with ram too much, even adjusting timings ruins ram, without making voltage higher.
You introduce new variables into the chain.
UNLESS...you have plenty of money to buy new stuff, then I guess you can do whatever you want.
I overclocked my CPUs for years, and I saw so much cpu migration on the chips, where it could not handle older clocks anymore, but was stable for a good year.
I saw even brand new i7 9700k go unstable within a day, after being stable, due to a motherboard voltage jumping up and down for no reason. Literally saw within several hours that CPU can no longer run above stock clock, unless you boost voltage to new levels.
I recently had a motherboard start fire.
I literally saw all components go bad, and in the end I wonder where is that fine line in overclocking, only Gods know where that is.
We are tinkering with stuff that is not really in our control, even though we are the ones that change settings and overclock.
I even had my GPU get ruined by overclocking +15 mv, old AMD 5790
They said it was safe, but it's far from truth.
Even electrical knowledge means nothing, as components have a mind of their own, and not made equal. Some RAM sticks are un-killable, others die from a gust of wind like my AMD 5790