Good evening Reaper19 and welcome back
Well depending on who made that MoBo it maybe video issue either onboard GVA chip or as you found out the add-on Video card.
I would be calling them up. Who ever you bought it from and do a RMA for another video card. The error you are getting
"Legacy Option Rom Initialization error" makes since that you can use the PC with out the video card.
If you look at part of the error you got "Rom" that means "Read only memory" the add-on video card has memory kind of like your MoBo has but the difference for the memory on the MoBo is "Ram" which is "Random access memory" this can read and write temporarily. But in some ways yes they both do the same thing and you would be right yes they do. But the video card memory only lets the info pass through and can not write, if I am making any since I hope
When you contact the vendor for the video card replacement I would ask them if your card can use HDMI as the default cable connection for your display although it should be able too but maybe you can use it but only as the second display and not as primary connection.
Hope this help you, Mike
PS please let us know how you make out.