So here is what I know. I recently bought parts for a new computer. I put it all together and everything worked apart from the graphics card (Sapphire AMD Radeon HD 7850). I was getting no video output from all of the ports on the graphic card, the fans spun up, but my monitor did not detect anything, and when I looked in the device manager via onboard graphics, there was no sign of it there either. I moved the graphics card to the pci x4 slot on my motherboard (a Gigabyte Z77-DS3H) and it worked fine. At first I thought the pci x16 slot must be faulty, but when I put the graphics card from my old computer (a AMD Radeon HD 7750) into the pci x16 slot on the new motherboard, it worked fine. I have tried installing the drivers for the card while it is in the pci x16 slot but it could not detect it. My bios is fully updated. I tried disabling onboard graphics but still got no video output. I am relatively new to this stuff so go slowly with me.
So, any ideas?
try reseating it again, firmly, and push it in all the way then check bios to see if bios senses the card while the dvi cable is connected to the mobo(assuming you have a igp in the intel chip). just to be sure, you have the 6 pin connected to the card right?