Ah, I called the company and they forgot to put the video cable with the card. there was no cable with the 256 card I replaced, so that's why I didn't know I should have received a cable.
I couldn't find a link to delete this posting.
I installed the ATI Radeon x1900 card (512MB) in my 2006 Mac Pro. Can't change resolution- it's at 1200x800 on my 30 in cinema monitor and there is a warning that my video cable needs to be plugged in. There is no video cable, the card just plugs in.
Any ideas? I did zap the pram.