Tl; dr: Linux on Ryzen is a pain at the moment.
Now for the long part: Our student council got new computers because the old ones where slow as hell. As one of the admins, the others and I together decided that ryzen would be a good option, because they are not that expensive and we wouldn't have to buy gpus. (Wrong decision it turns out.) We settled on the ryzen 3 2200G and bought three systems to replace the old ones.

We meet Saturday morning and build the systems. All was fine and we were happy. The we tried to install ubuntu via preseeded netboot, which seemed to work fine at first. Then we started having weird screen issues and couldn't proceed with the installation. (See image) we then grumpily decided to just install them all one by one, flashed two usbs and started installing. On two systems the installation worked and we installed our packages, we weren't so lucky with the third one. It would crash on us all the time, even in bios. While that was going on we tried to set the other two up, turns out those two were also crashing but not as frequent as the other one. So we start to google and find people saying that kernel 4.19 kinda fixes it. We install it on the two working machines and the crashes get less frequent but are still there. At that point it was midnight and we went home.
Sunday morning: we reseated the cpu on the third system and it seems to be better now (it installed on the second try) and we were able to change the kernel. Yay. Now all three are in a state where they will sometimes randomly reset. :/ and we don't know what to try anymore.... Any suggestions?