I just bought an ATI Radeon 4650 PCI-Express graphics cards for my Dell Inspiron 580. I looked up the information on the Dell site to figure out what BUS I needed and discovered it was this x16 Express PCI so that's what I ordered. Well I'm not SUPER new to computers, but new to Dell machines. I tried first to boot to BIOS and disable onboard video, but there's no option to do so. So then I tried to boot the computer back up with the old video card and disable the onboard video through the Device Manager. I re-installed the new card and whenever the card is in the PC, the computer powers up but doesn't boot and nothing appears on the display... Regardless of which video port the monitor is plugged into... Maybe the 300w power supply isn't enough for the video card? I'm confused... Any ideas?