Does it mean it won't work corectly ? Or nobdy tried and i'll do a crash test, sorta?
No, it means that MSI did not test them on that board. If you start your machine with only one module installed for a start and then manually adjust that in your BIOS to a typical 1333 speed at 126.96.36.199 timings at 1,5V, they should work. You can then add the other stick afterwards. Once you have that stable, then you can start experimenting with higher speeds.