Update:
This problem was propably caused by my DDR 4000Mhz RAM. Still everything was fine in World of tanks with ultra settings in 4K, with those mems. I found out that crashes were avoided with in-game graphics setting "reduce GUI refresh rate", which sounds weird, but it helped (still with ddr4 4000Mhz). Still there was some jigjagging and visual problems, so I reduced my Mhz of RAM a little bit. Now it looks like it's ok, but not sure yet. I haven't put that GUI setting back yet. Will try later. It was not so pleaseant to be pinky so a lot. It would be fair, in my opinion, to not punish for leaving from "co-op" because of computer problems.