Since PCI has no locking mechanism, it could be your cable that's lifting the board. Strain relief is one way. This could require some creative thinking. One way could be to use cable ties and mounts positioned in such a way that the card is held down. It might also be that the particular slot you selected doesn't grip well. You could try another slot. I've also found that sometimes motherboards don't align perfectly to allow cards to both seat well when the rear screw is tightened. This can sometimes be improved by loosening the MB screws, installing add in cards to where they fit without stress and then snug the MB screws. You might be able to loosen the mounting bracket on your video card as well and re-tighten the screws in a fashion that provides the best fit. Good luck.
I have a HP desktop/tower with a GEFORCE 8400 GS -- a PCI video card.
Occasionaly the screen goes blank and the only way to fix it is to open the case and lift up on end of the video card for a few seconds. The monitor signal goes from dead to active, and then the screen starts working and stays working for an hour or so. It's better than a blank screen but it's only a temporary fix.
Anyone know how to fix this problem for good? I've cleaned, tightened and snugged everything I can think of and I'm considering replacing the video card entirely.