Solved: Apparently the card did work. Just, for whatever reason, the board didn't like the DsiplayPort until settings were changed. Using HDMI was fine.
I got a used Aurora R10 with no graphics off eBay. Unfortunately, I can't just stick my old card in it thanks to SecureBoot. I can't change the BIOS setting because that would require a working graphics card to see. What are the options? Will any Dell PCIe card work? Like, if I find a six-year-old Dell Office machine & borrow its card, would that get me through? Is there any way to do this without the card?
Aurora R10, no GPU used system & SecureBoot