Thanks for all the suggestions so far!
I have not installed Win10 on the machine. It currently is a Win7 Home Premium that I try to upgrade to Win10 primarily through the install disc from Microsoft.
It did not start installing Win10 and when I return to the currently installed Win7 it is almost entirely unresponsive, so downloading something and running a diagnostic with it are out of the question. The original install is German and I confused the thing that restores your boot sector with the system restoration. Running troubleshooting on a German OS with English guides can be horse dung sometimes.
That being said, The device was a high end custom build in 2012. Win7 never had driver issues and none of the parts in the machine are old enough to have driver support discontinued.
I also doubt that the hardware got damaged somehow over the span of 20 minutes between it running like a kitten playing Overwatch and me trying to install Win10 on it.
So right now my situation is that I can't run any diagnostics on the machine on the Win7 install and attempts to install Win10 result in the error above. I'll try a fresh Win7 Install from disc next, maybe it will at least respond to that and allow me to upgrade to Win10 from that point.
Merry Christmas everyone!