Did you connect up the card properly?
Yes, I seated the card, reseated the card, re-connected the PCI-E connectors. When I took off onboard graphics from the BIOS and used the card, the case speaker made four beeps; one long followed by three short. When I searched this, it came up as something like "bad video memory or no video card present". I suppose this means it's more likely that the card is broken?