Hello, I was working on my PC using my onboard graphics trying to get my graphics card to handle itself while taking a full load. I think I handled that, so after I reinserted my card, it booted up with a loud tone. Whoops, I forgot to plug in the power connectors to my 8800GTX. Now it won't display anything to my monitor.
I'm a very tech savvy guy, but this one is way over my head. I tried to reset the CMOS, checked and rechecked all of my cables, reseated the card millions of times. The computer boots up and works with my onboard graphics, but when I try to boot with my 8800GTX, it doesn't display anything on the screen.
Try the card with another PC, but, I have seen cards go bad and then then fry the PCIe slot on the PC they are used in. A guy at work brought in his video card that seemed to be killing his motherboard, I tried it on a HP Workstation, killed the motherboard soon as it powered on. Luckily it was in warranty.
So you need to test the video card to rule out any issues with the PC, but you have a chance of killing the test motherboard so don't use anything expensive to test it with.