So I bought an hp pavilion desktop i3 3240 computer and a geforce gtx 650 Ti graphics card, the stock computer uses intel 2500 for graphics, I installed the new graphics card and plugged a tr 450 watt power thing to the graphics card, plugged the VGA into the graphics card slot and when I turn the computer on the screen just stays black like its not hooked up visually...any help? Thanks!!!