Ok I recently bought a Radeon 9100 pci card from Tiger Direct and I put it into a computer and it wouldnt display anything (I previously had a PCI video card in there so the bios was set up for a PCI video card). My first thoughts were the power supply so I exchanged it with a 300W and it still did the same thing. So I put the old video card back in so I could access the bios and I checked all the settings and they were all set up how Im pretty sure they should be set up. I have two more computers in my house, one of them did the exact same thing when I put in the video card (wouldnt acces bios or anything). I installed it in my new computer along with my 9700 so I could see if I could get anything. The computer started up normaly and when I got into windows it saw that there was another video card installed. So I plugged my monitor into it and I got it to work after going back in forth between my control panel and both my video cards. So after this I thought hey maybe if I put my old video card in with my 9100 I could see if I could get anything (I only had the two cards in together to see if the bios would even start up). So I tried this and it does nothing. The screen stays blank no matter what I do. So now Im really confused on why it wont work. I never ran any tests to see how well it worked on my good computer but I know it gives off a picture at least. So if you have any ideas please help me. Thanks.

Make sure that the 9100 is fully inserted. Sometimes a video card needs a healty push to fully seat.

If that's ok, then make sure that it does not feel loose in the slot.

If ok, then insert it without installing the hold down screw.
If that works, then the metal ear on the card where the screw is inserted is bent out of true, and the card is slightly raising out of the slot when the screw is fully tightened.
You can rebend the ear with a pair of needle nose pliars.

If no luck with that, and the 9100 was inserted in the same slot as the old card, then the 9100 is probably bad.
RMA it for a replacement.