The list on the webpage contains RAMs that were tested, not all compatible models, so I am not sure if there is any compatibility issue. All in all, I haven't got this issues today, after I did the following steps, which summarize most suggestions I have received before.
Reconfirmed GPU's power supply cables were sitting tight
Loaded bios defaults, then set RAM speed from auto to 2133MHz
Did a clean windows 8.1 install
On the first setup page I disabled automatic updates for drivers
Installed VCRedist 2005-2015 first, as CCC and AMD Settings would require those later, and in case of not finding them, an error would occur during installation
Installed all drivers found on motherboard's website
Then I launched IE and turned hardware accelaration off
Installed all windows 8.1 updates that vere due, including DX and NET Framework, restarted
Installed latest AMD Omega driver, changed Video -> Color to non default (as some people had driver crashes fixed this way)
Downclocked GPU from nominal 1050 for core and 1400 for memory to 950/1250, saved settings, restarted
Launched Fur Mark, did a test for a couple of minutes, average fps was 27 in contrary to 28 with nominal clock values, so not much of a loss, GPU temps were lower for 10C than when I had the side panel removed (guess cable management and new fan allocation did their job)
Launched a game and played for an hour or two, getting around 99% gpu load with new clock values and a maximum of 71C temperature (in contrary to 86C before), fps didn't suffer much if not at all
received no driver crashes or bsod during the whole day
So I hope current state will be permanent, if I don't get any errors for a long period of time, guess the problem is solved
Thank you for all suggestions, I will post in case I do get new crashes. In case I don't, I will still post in a month or so to let anyone to whom it may concern know that at least one of the steps mentioned above fixed the problem.