Check the computer manual or BIOS manual for beep codes (if they are short or long beeps, or how many beeps you get, these are all specific code for each problems so the beeps should tell you exactly what the problem is).
For the video card, make sure it's properly seated and that your PSU is feeding enough power (does your video card requires additional 6-pin power connectors from the PSU? What video card and PSU do you have?). If your video cable was connected to the integrated card you need to connect it to your video card now. Also, what cable interface are you using to connect the video card to your monitor? DVI? VGA? HDMI? Displayport? Make sure your monitor is set to the right input.