Rare memory errors at 3200 in seemingly stable system

[tHE_uKER]

I have some F4-3200C14D-8GVK (2x8 GB, Samsung B-die) on an ASUS Prime V350 PLUS (latest BIOS).
Just selecting DOCP, the system boots into Windows, and appears stable, often withstanding extended sessions of Just Cause 4 and other "heavy" games, but eventually instability will come up.

Entering some missing timings from the XMP 2.0 profile that the mother decides to ignore, and upping the SOC voltage to 1.1v and the DRAM voltage to 1.4v I think helped, as the system has since endured some 3 hours of MemTest64.
Strange thing is, there's other times MemTest craps out before the first 10 minutes, or the system BSODs or freezes as Windows starts or shortly after, without doing anything too special.
I've monitored the modules' temps with HWinfo64 and even after several hours of MemTest, the temps hardly reach 50ºC.

Needless to say, with the memory at 2133 there's no stability issues.

Any suggestions?
The system seems so close to being stable, but I can't just forget about it and go on with life because of these rare errors.

Any ideas will be greatly appreciated.

PS: One crazy theory I have is that the system is stable only on the same boot as I set the memory timings in the BIOS. The moment I reboot it reverts to some unstable config.
But that's just an "out there" theory of mine that I have yet to confirm.

[GSKILL TECH]

Have you tried each individual stick to see if error occurs with one or both modules?

Did you try 2933 to see if it can be stable?

[tHE_uKER]

Hi there. Thanks for the reply.

No, I haven't tested the modules one by one.
Do you suspect one could be faulty?
Even when they go just fine through 4+ hours of MemTest64, even at 3200?

Haven't tested lower speeds either, as I won't use them at anything but 3200.

The kit works perfectly at 2133 MHz (over 8 hours of MemTest64 attest to this), so if I can't get them to work I'd very much rather sell them and get something else.

I do hope to figure it out though.

Any suggestions?

[GSKILL TECH]

Errors can be hidden when tested together.

It is also odd because if the system clears memtest then there should be no issues.

If you would like, send them in for RMA to see if a new kit works better.

[tHE_uKER]

Yeah, I tried Windows' memory diagnostic today and it cleared too.
I have run AIDA64 too (though not for too long, maybe half an hour) and it didn't find issues.

About returning them, nah, I appreciate the suggestion, but I'm not in the US, and the kit was purchased quite long ago.
Would be quite the hassle to do so.
I'll try to sort it out, and sell them if it doesn't work out.

For the time being, with the memory at 1.4v the system seems pretty stable. Haven't had any issues today.
If anything came up, I'll see if upping the DDR voltage to 1.45 helps.
I've heard that B-dies like voltage and have no issues even over 1.5.

I'll let you know how it goes.
If you, or anyone else, can think of anything else that could help, it will be welcome.

Thanks again!

[tHE_uKER]

Well, things are going pretty well I think, but something new came up.

While the system does pass 4 hours of MemTest64, it seems like gaming is not as stable.
Just Cause 4 is crashing after less than an hour of gameplay.

Is there anything that can be causing the RAM to fail under more CPU-intensive scenarios?

Thanks in advance.

[GSKILL TECH]

If the RAM is error free, then it is a matter of BIOS settings. That is if the RAM is indeed causing the issue.