I thought I did a lot of research before I got all the parts for my build but like you say sometimes issues don't become apparent until you've actually finished the build. I didn't even realize that GPU passthrough was something I would want to do, to be honest, so I guess I'm lucky that I was able to resolve the issue. Lucky too that since the GPUs I ended up getting are fairly old, Amazon was the only place I could find them so returning the first one wasn't a problem.