1. It's fine. RAM (no matter what it is) at this point generally handles up to about 1.5V. I honestly recommend not going any higher than 1.45V, but that's just me. Most memory is made to run at 1.35V. As far as problems, you could have issues like you're seeing. The best way to find out, is set it to 1.4V and try the games and such.
2. Memory compatibility is largely based on the type of memory used. However, we really do not recommend mixing modules.
3. It really depends. Generally, XMP has worked OK. But it's definitely not perfect.
What I might suggest is taking the NB/SoC voltage up to 1.1V, maybe 1.2V. Both of those should still be OK. These can help deal with issues like you 're seeing.
I would also probably suggest looking at the AM4 overclocking guide, specifically the section on memory. See : https://forum-en.msi.com/index.php?topic=286610.0
Hello, thanks for the answer.
1. From what you say I presume low profile memory can run also on high profile voltages, am I right? What concerns me mostly is that native voltage for this ram is 1.2, but mobo set in auto uses it at 1.184v 95% of the time... I was always kinda afraid touching voltages, but I wondered if the ones used by motherboeard on default could harm memory/memory performance more than actually setting it to a fixed voltage....
2. I didn't mix modules, they're the same ram both of them, but I couldn't afford purchasing a 8x2 kit when I built this machine, so I obtained a second module a while later. The older module works perfectly (tested yesterday night again too, no crashes of any sort, no unstability until resources were ultimately off), the newer module works really bad no matter what (but as I said they're identical). I was wondering more about compatibility
precisely between this ram model and cpu, both in single and dual channel (because this specific module is not listed in the MSI website, so I hoped someone that tried it could share its knowledge about it), never meant to try a dual channel with different modules...
Purchasing these new components was quite difficult for me; in my country you can't really choose as you please, memory selection (as well as motherboards selection and prices) is really poor, so I had to pick a random one in the end, basing on opinions around... the only memory from this MB's compatibility list available in our shops was a crucial, but it wasn't available where I purchased, so I had to pick this Corsair... There were also some Gskills models, but none of them was also listed in that list.3. So I suppose mine is working ok too. Glad to hear that.

I forgot to specify it yesterday, at that point modifying post was not working so I let it go...
I didn't oc the ram, I didn't oc the cpu.
Considering that my older module has no problems to run, do you still advice modifying voltages of NB?
I'm going to bring the newer module back to the shop and ask to try another, so we'll see if my issues were related to compatibility or the module was actually misbehaving.
I'll also take a look to the thread you suggested, my concern is stability tho, I don't plan overclocking the memory (specially not on a low end machine like this, I should have to overclock the whole system at that point, and I doubt my psu would be enough).