Recently purchased Acer X1300 which has Geforce 8200 onboard graphics, I decided to upgrade to Geforce GTX9400 which is PCI. I uninstalled the onboard graphics, turned off PC then installed new card and started up with cable in new card. Computer starts can even hear the windows starting up but no display. When i plug the cable back into the onboard after turning off PC still get nothing. If i then turn off and pull the new card and restart everything is fine, only on standard VGA display. Any help appreciated in overcoming this problem.
Try this..Boot with the onboard and then go to device manager, under display adapters right click on your video card and select disable..then shut down the pc and insert your new PCI card and see what happens..also you may want to go into the bios and make sure pci is selected for the graphics, this is not needed most of the time but it just depends on the motherboard you have..hope it helps
Done all of this previously, after plenty of messing around I have finally got card working to a point. When start up computer all seems fine, usual boot screen etc, however just as it gets to windows screen, screen goes blank and display shows no cable connected. I can however start PC in safe mode.
Before you install a new video card, you need to uninstall the drivers from Windows that run your old hardware, completely. Then shutdown, install the new card, let the system boot, and Windows will detect your new card, and install the generic VGA drivers. This will get you into Windows, and then you can install your new drivers for your new card. This is the very FIRST thing you should do, before you disable your onboard video.